IDL Version 5.4September, 2000 EditionCopyright Research Systems, Inc.All Rights Reserved

IDL ReferenceGuide

Restricted Rights NoticeThe IDL software program and the accompanying procedures, functions, and documenta-tion described herein are sold under license agreement. Their use, duplication, and disclo-sure are subject to the restrictions stated in the license agreement. Research Systems, Inc.,reserves the right to make changes to this document at any time and without notice.

Limitation of WarrantyResearch Systems, Inc. makes no warranties, either express or implied, as to any matter notexpressly set forth in the license agreement, including without limitation the condition ofthe software, merchantability, or fitness for any particular purpose.Research Systems, Inc. shall not be liable for any direct, consequential, or other damagessuffered by the Licensee or any others resulting from use of the IDL software package or itsdocumentation.

Permission to Reproduce this ManualIf you are a licensed user of this product, Research Systems, Inc. grants you a limited, non-transferable license to reproduce this particular document provided such copies are for youruse only and are not sold or distributed to third parties. All such copies must contain thetitle page and this notice page in their entirety.

AcknowledgmentsIDL is a registered trademark of Research Systems Inc., registered in the United States Patent and Trademark Office, forthe computer program described herein. Software Vision is a trademark of Research Systems, Inc.Numerical Recipes is a trademark of Numerical Recipes Software. Numerical Recipes routines are used by permission.GRG2 is a trademark of Windward Technologies, Inc. The GRG2 software for nonlinear optimization is used by permis-sion.NCSA Hierarchical Data Format (HDF) Software Library and UtilitiesCopyright 1988-1998 The Board of Trustees of the University of IllinoisAll rights reserved.CDF LibraryCopyright 1999National Space Science Data CenterNASA/Goddard Space Flight CenterNetCDF LibraryCopyright 1993-1996 University Corporation for Atmospheric Research/UnidataHDF EOS LibraryCopyright 1996 Hughes and Applied Research CorporationThis software is based in part on the work of the Independent JPEG Group.This product contains StoneTable, by StoneTablet Publishing. All rights to StoneTable and its documentation areretained by StoneTablet Publishing, PO Box 12665, Portland OR 97212-0665. Copyright 1992-1997 StoneTablet Publish-ingWASTE text engine 1993-1996 Marco PiovanelliPortions of this software are copyrighted by INTERSOLV, Inc., 1991-1998.Other trademarks and registered trademarks are the property of the respective trademark holders.

IDL Reference Guide 3

ContentsReference:IDL Commands Reference ................................................................... 41IDL Syntax ....................................................................................................................... 42

Elements of Syntax .................................................................................................... 43Procedures ................................................................................................................. 44Functions ................................................................................................................... 45Arguments ................................................................................................................. 45Keywords ................................................................................................................... 45

.COMPILE ....................................................................................................................... 48

.CONTINUE .................................................................................................................... 49

.EDIT ............................................................................................................................... 50

.FULL_RESET_SESSION .............................................................................................. 51

.GO ................................................................................................................................... 52

.OUT ................................................................................................................................ 53

.RESET_SESSION .......................................................................................................... 54

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.RETURN ........................................................................................................................ 56

.RNEW ............................................................................................................................. 57

.RUN ................................................................................................................................ 59

.SKIP ................................................................................................................................ 61

.STEP ............................................................................................................................... 62

.STEPOVER .................................................................................................................... 63

.TRACE ........................................................................................................................... 64A_CORRELATE ............................................................................................................. 65ABS .................................................................................................................................. 67ACOS ............................................................................................................................... 68ADAPT_HIST_EQUAL .................................................................................................. 69ALOG .............................................................................................................................. 71ALOG10 .......................................................................................................................... 72AMOEBA ........................................................................................................................ 73ANNOTATE .................................................................................................................... 77

Using the Annotation Widget .................................................................................... 77ARG_PRESENT .............................................................................................................. 79ARRAY_EQUAL ............................................................................................................ 81ARROW .......................................................................................................................... 82ASCII_TEMPLATE ........................................................................................................ 84ASIN ................................................................................................................................ 86ASSOC ............................................................................................................................ 87ATAN .............................................................................................................................. 90AXIS ................................................................................................................................ 91BAR_PLOT ..................................................................................................................... 95BEGIN...END .................................................................................................................. 99BESELI .......................................................................................................................... 101BESELJ .......................................................................................................................... 103BESELK ........................................................................................................................ 105BESELY ........................................................................................................................ 107BETA ............................................................................................................................. 109BILINEAR ..................................................................................................................... 110BIN_DATE .................................................................................................................... 112BINARY_TEMPLATE ................................................................................................. 113BINDGEN ..................................................................................................................... 115BINOMIAL ................................................................................................................... 116

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BLAS_AXPY ................................................................................................................ 118BLK_CON ..................................................................................................................... 120BOX_CURSOR ............................................................................................................. 122

Using BOX_CURSOR ............................................................................................ 122BREAK .......................................................................................................................... 124BREAKPOINT .............................................................................................................. 125BROYDEN .................................................................................................................... 128BYTARR ....................................................................................................................... 131BYTE ............................................................................................................................. 132BYTEORDER ................................................................................................................ 133

Note On IEEE to VAX Format Conversion ............................................................ 136BYTSCL ........................................................................................................................ 137C_CORRELATE ........................................................................................................... 139CALDAT ....................................................................................................................... 141CALENDAR .................................................................................................................. 144CALL_EXTERNAL ...................................................................................................... 145

Note On IEEE to VAX Format Conversion ............................................................ 151String Parameters .................................................................................................... 152Calling Convention .................................................................................................. 152Portable .................................................................................................................... 153

CALL_FUNCTION ....................................................................................................... 159CALL_METHOD .......................................................................................................... 160CALL_PROCEDURE ................................................................................................... 161CASE ............................................................................................................................. 162CATCH .......................................................................................................................... 164CD .................................................................................................................................. 166CDF Routines ................................................................................................................ 169CEIL ............................................................................................................................... 170CHEBYSHEV ................................................................................................................ 171CHECK_MATH ............................................................................................................ 172CHISQR_CVF ............................................................................................................... 178CHISQR_PDF ............................................................................................................... 179CHOLDC ....................................................................................................................... 181CHOLSOL ..................................................................................................................... 182CINDGEN ...................................................................................................................... 184CIR_3PNT ..................................................................................................................... 185

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CLOSE ........................................................................................................................... 187CLUST_WTS ................................................................................................................ 189CLUSTER ...................................................................................................................... 191COLOR_CONVERT ..................................................................................................... 193COLOR_QUAN ............................................................................................................ 195

Using COLOR_QUAN ........................................................................................... 195COLORMAP_APPLICABLE ....................................................................................... 199COMFIT ........................................................................................................................ 200COMMON ..................................................................................................................... 203COMPILE_OPT ............................................................................................................ 204COMPLEX .................................................................................................................... 207COMPLEXARR ............................................................................................................ 209COMPLEXROUND ...................................................................................................... 210COMPUTE_MESH_NORMALS .................................................................................. 211COND ............................................................................................................................ 212CONGRID ..................................................................................................................... 213CONJ ............................................................................................................................. 216CONSTRAINED_MIN ................................................................................................. 217CONTINUE ................................................................................................................... 224CONTOUR .................................................................................................................... 225

Smoothing Contours ................................................................................................ 225CONVERT_COORD .................................................................................................... 238CONVOL ....................................................................................................................... 241

Using CONVOL ...................................................................................................... 241COORD2TO3 ................................................................................................................ 245CORRELATE ................................................................................................................ 247COS ................................................................................................................................ 249COSH ............................................................................................................................. 250CRAMER ...................................................................................................................... 251CREATE_STRUCT ...................................................................................................... 253CREATE_VIEW ........................................................................................................... 255CROSSP ........................................................................................................................ 258CRVLENGTH ............................................................................................................... 259CT_LUMINANCE ........................................................................................................ 261CTI_TEST ..................................................................................................................... 263CURSOR ....................................................................................................................... 265

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CURVEFIT .................................................................................................................... 268CV_COORD .................................................................................................................. 272CVTTOBM .................................................................................................................... 274CW_ANIMATE ............................................................................................................. 276

Using CW_ANIMATE ............................................................................................ 276CW_ANIMATE_GETP ................................................................................................. 281CW_ANIMATE_LOAD ................................................................................................ 283

Example ................................................................................................................... 284CW_ANIMATE_RUN .................................................................................................. 285CW_ARCBALL ............................................................................................................ 287

Using CW_ARCBALL ........................................................................................... 287CW_BGROUP ............................................................................................................... 291CW_CLR_INDEX ......................................................................................................... 296CW_COLORSEL .......................................................................................................... 299

Using CW_COLORSEL ......................................................................................... 299CW_DEFROI ................................................................................................................. 301CW_FIELD .................................................................................................................... 305CW_FILESEL ................................................................................................................ 309CW_FORM .................................................................................................................... 313

Using CW_FORM ................................................................................................... 313CW_FSLIDER ............................................................................................................... 321

Using CW_FSLIDER .............................................................................................. 321CW_LIGHT_EDITOR .................................................................................................. 325CW_LIGHT_EDITOR_GET ......................................................................................... 329CW_LIGHT_EDITOR_SET ......................................................................................... 332CW_ORIENT ................................................................................................................ 334CW_PALETTE_EDITOR ............................................................................................. 336CW_PALETTE_EDITOR_GET ................................................................................... 342CW_PALETTE_EDITOR_SET .................................................................................... 343CW_PDMENU .............................................................................................................. 344CW_RGBSLIDER ......................................................................................................... 351

Using CW_RGBSLIDER ........................................................................................ 351CW_TMPL .................................................................................................................... 354CW_ZOOM ................................................................................................................... 355

Using CW_ZOOM .................................................................................................. 355DBLARR ....................................................................................................................... 360

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DCINDGEN .................................................................................................................. 361DCOMPLEX ................................................................................................................. 362DCOMPLEXARR ......................................................................................................... 364DEFINE_KEY ............................................................................................................... 365

Defining New Function Keys .................................................................................. 372DEFROI ......................................................................................................................... 374

Using DEFROI ........................................................................................................ 374DEFSYSV ...................................................................................................................... 376DELETE_SYMBOL ...................................................................................................... 378DELLOG ....................................................................................................................... 379DELVAR ....................................................................................................................... 380DERIV ........................................................................................................................... 381DERIVSIG ..................................................................................................................... 382DETERM ....................................................................................................................... 383DEVICE ......................................................................................................................... 385DFPMIN ........................................................................................................................ 389DIALOG_MESSAGE ................................................................................................... 392DIALOG_PICKFILE .................................................................................................... 395DIALOG_PRINTERSETUP ......................................................................................... 398DIALOG_PRINTJOB ................................................................................................... 400DIALOG_READ_IMAGE ............................................................................................ 402DIALOG_WRITE_IMAGE .......................................................................................... 405DIGITAL_FILTER ........................................................................................................ 407DILATE ......................................................................................................................... 409

Using DILATE ........................................................................................................ 410DINDGEN ..................................................................................................................... 414DISSOLVE .................................................................................................................... 415DIST .............................................................................................................................. 416DLM_LOAD ................................................................................................................. 417DLM_REGISTER ......................................................................................................... 418DO_APPLE_SCRIPT .................................................................................................... 419DOC_LIBRARY ........................................................................................................... 421DOUBLE ....................................................................................................................... 424DRAW_ROI .................................................................................................................. 426EFONT .......................................................................................................................... 428EIGENQL ...................................................................................................................... 430

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EIGENVEC .................................................................................................................... 433ELMHES ........................................................................................................................ 435EMPTY .......................................................................................................................... 436ENABLE_SYSRTN ...................................................................................................... 437

Special Cases ........................................................................................................... 438EOF ................................................................................................................................ 439

Using EOF with VMS Files .................................................................................... 439EOS_* Routines ............................................................................................................. 441ERASE ........................................................................................................................... 442ERODE .......................................................................................................................... 444

Using ERODE ......................................................................................................... 445ERRORF ........................................................................................................................ 449ERRPLOT ...................................................................................................................... 450EXECUTE ..................................................................................................................... 452EXIT .............................................................................................................................. 453EXP ................................................................................................................................ 454EXPAND ....................................................................................................................... 455EXPAND_PATH ........................................................................................................... 456

The Path Definition String ...................................................................................... 456EXPINT ......................................................................................................................... 460EXTRAC ........................................................................................................................ 462EXTRACT_SLICE ........................................................................................................ 464F_CVF ........................................................................................................................... 468F_PDF ............................................................................................................................ 469FACTORIAL ................................................................................................................. 471FFT ................................................................................................................................. 473

Running Time .......................................................................................................... 475FILE_CHMOD .............................................................................................................. 477FILE_DELETE .............................................................................................................. 481FILE_EXPAND_PATH ................................................................................................ 483FILE_MKDIR ................................................................................................................ 485FILE_TEST .................................................................................................................... 486FILE_WHICH ................................................................................................................ 490FILEPATH ..................................................................................................................... 491FINDFILE ...................................................................................................................... 493FINDGEN ...................................................................................................................... 495

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FINITE ........................................................................................................................... 496FIX ................................................................................................................................. 498FLICK ............................................................................................................................ 500FLOAT .......................................................................................................................... 501FLOOR .......................................................................................................................... 502FLOW3 .......................................................................................................................... 504FLTARR ........................................................................................................................ 506FLUSH ........................................................................................................................... 507FOR ................................................................................................................................ 508FORMAT_AXIS_VALUES .......................................................................................... 509FORWARD_FUNCTION ............................................................................................. 510FREE_LUN ................................................................................................................... 511FSTAT ........................................................................................................................... 513FULSTR ........................................................................................................................ 516FUNCT .......................................................................................................................... 518FUNCTION ................................................................................................................... 519FV_TEST ....................................................................................................................... 520FX_ROOT ..................................................................................................................... 522FZ_ROOTS .................................................................................................................... 524GAMMA ........................................................................................................................ 526GAMMA_CT ................................................................................................................ 527GAUSS_CVF ................................................................................................................ 528GAUSS_PDF ................................................................................................................. 529GAUSS2DFIT ............................................................................................................... 531

Procedure Used and Other Notes ............................................................................ 531GAUSSFIT .................................................................................................................... 534GAUSSINT .................................................................................................................... 537GET_DRIVE_LIST ....................................................................................................... 538GET_KBRD .................................................................................................................. 539GET_LUN ..................................................................................................................... 541GET_SCREEN_SIZE .................................................................................................... 542GET_SYMBOL ............................................................................................................. 543GETENV ....................................................................................................................... 544

Environment Variables Under VMS ....................................................................... 544Special Handling of the IDL_TMPDIR Environment Variable ............................. 545The UNIX Environment .......................................................................................... 545

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GOTO ............................................................................................................................ 547GRID_TPS ..................................................................................................................... 548GRID3 ............................................................................................................................ 551GS_ITER ........................................................................................................................ 554H_EQ_CT ...................................................................................................................... 557H_EQ_INT ..................................................................................................................... 558

Using the H_EQ_INT Interface .............................................................................. 558HANNING ..................................................................................................................... 559HDF_* Routines ............................................................................................................ 560HDF_BROWSER .......................................................................................................... 561

Graphical User Interface Menu Options ................................................................. 562HDF_READ ................................................................................................................... 565

Graphical User Interface Menu Options ................................................................. 566HEAP_GC ...................................................................................................................... 569HELP .............................................................................................................................. 571HILBERT ....................................................................................................................... 578HIST_2D ........................................................................................................................ 579HIST_EQUAL ............................................................................................................... 581HISTOGRAM ................................................................................................................ 584HLS ................................................................................................................................ 590HOUGH ......................................................................................................................... 592HQR ............................................................................................................................... 600HSV ................................................................................................................................ 602IBETA ............................................................................................................................ 604IDENTITY ..................................................................................................................... 606IDL_Container Object Class .......................................................................................... 607IDLanROI Object Class ................................................................................................. 608IDLanROIGroup Object Class ....................................................................................... 609IDLffDICOM Object Class ............................................................................................ 610IDLffDXF Object Class ................................................................................................. 611IDLffLanguageCat Object Class .................................................................................... 612IDLffShape Object Class ............................................................................................... 613IDLgr* Object Classes ................................................................................................... 614IF...THEN...ELSE .......................................................................................................... 615IGAMMA ...................................................................................................................... 616IMAGE_CONT .............................................................................................................. 619

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Contents IDL Reference Guide

IMAGE_STATISTICS .................................................................................................. 620IMAGINARY ................................................................................................................ 623INDGEN ........................................................................................................................ 624INT_2D .......................................................................................................................... 626INT_3D .......................................................................................................................... 629INT_TABULATED ....................................................................................................... 632INTARR ........................................................................................................................ 634INTERPOL .................................................................................................................... 635INTERPOLATE ............................................................................................................ 637INVERT ......................................................................................................................... 641IOCTL ............................................................................................................................ 643ISHFT ............................................................................................................................ 646ISOCONTOUR .............................................................................................................. 647ISOSURFACE ............................................................................................................... 650JOURNAL ..................................................................................................................... 652JULDAY ........................................................................................................................ 653KEYWORD_SET .......................................................................................................... 656KRIG2D ......................................................................................................................... 657KURTOSIS .................................................................................................................... 661KW_TEST ..................................................................................................................... 662L64INDGEN .................................................................................................................. 665LABEL_DATE .............................................................................................................. 666LABEL_REGION ......................................................................................................... 670LADFIT ......................................................................................................................... 672LAGUERRE .................................................................................................................. 674LEEFILT ........................................................................................................................ 676LEGENDRE .................................................................................................................. 678LINBCG ........................................................................................................................ 681LINDGEN ...................................................................................................................... 684LINFIT ........................................................................................................................... 685LINKIMAGE ................................................................................................................. 688

VMS LINKIMAGE and LIB$FIND_IMAGE_SYMBOL ..................................... 691LIVE_Tools ................................................................................................................... 694LIVE_CONTOUR ......................................................................................................... 695LIVE_CONTROL ......................................................................................................... 703LIVE_DESTROY .......................................................................................................... 706

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LIVE_EXPORT ............................................................................................................. 708LIVE_IMAGE ............................................................................................................... 711LIVE_INFO ................................................................................................................... 718

Structure Tables for LIVE_INFO and LIVE CONTROL ....................................... 719LIVE_LINE ................................................................................................................... 729LIVE_LOAD ................................................................................................................. 733LIVE_OPLOT ................................................................................................................ 734LIVE_PLOT .................................................................................................................. 739LIVE_PRINT ................................................................................................................. 747LIVE_RECT .................................................................................................................. 749LIVE_STYLE ................................................................................................................ 753LIVE_SURFACE .......................................................................................................... 760LIVE_TEXT .................................................................................................................. 768LJLCT ............................................................................................................................ 772LL_ARC_DISTANCE ................................................................................................... 773LMFIT ............................................................................................................................ 775LMGR ............................................................................................................................ 780LNGAMMA .................................................................................................................. 783LNP_TEST .................................................................................................................... 784LOADCT ....................................................................................................................... 787LOCALE_GET .............................................................................................................. 789LON64ARR ................................................................................................................... 790LONARR ....................................................................................................................... 791LONG ............................................................................................................................ 792LONG64 ........................................................................................................................ 793LSODE ........................................................................................................................... 794LU_COMPLEX ............................................................................................................. 799LUDC ............................................................................................................................. 801LUMPROVE .................................................................................................................. 803LUSOL ........................................................................................................................... 805M_CORRELATE .......................................................................................................... 807MACHAR ...................................................................................................................... 809

MACHAR Fields ..................................................................................................... 809MAKE_ARRAY ............................................................................................................ 811MAKE_DLL .................................................................................................................. 814MAP_2POINTS ............................................................................................................. 820

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Contents IDL Reference Guide

MAP_CONTINENTS .................................................................................................... 824MAP_GRID ................................................................................................................... 828MAP_IMAGE ................................................................................................................ 833MAP_PATCH ................................................................................................................ 837MAP_PROJ_INFO ........................................................................................................ 841MAP_SET ...................................................................................................................... 843MATRIX_MULTIPLY ................................................................................................. 854MAX .............................................................................................................................. 856MD_TEST ..................................................................................................................... 858MEAN ............................................................................................................................ 860MEANABSDEV ............................................................................................................ 861MEDIAN ....................................................................................................................... 863MEMORY ..................................................................................................................... 865MESH_CLIP .................................................................................................................. 868MESH_DECIMATE ...................................................................................................... 870MESH_ISSOLID ........................................................................................................... 872MESH_MERGE ............................................................................................................ 873MESH_NUMTRIANGLES ........................................................................................... 875MESH_OBJ ................................................................................................................... 876MESH_SMOOTH ......................................................................................................... 882MESH_SURFACEAREA ............................................................................................. 884MESH_VALIDATE ...................................................................................................... 886MESH_VOLUME ......................................................................................................... 888MESSAGE ..................................................................................................................... 889MIN ................................................................................................................................ 891MIN_CURVE_SURF .................................................................................................... 893MK_HTML_HELP ........................................................................................................ 898MODIFYCT .................................................................................................................. 901MOMENT ...................................................................................................................... 903MORPH_CLOSE .......................................................................................................... 905MORPH_DISTANCE ................................................................................................... 908MORPH_GRADIENT ................................................................................................... 911MORPH_HITORMISS .................................................................................................. 913MORPH_OPEN ............................................................................................................. 916MORPH_THIN .............................................................................................................. 919MORPH_TOPHAT ....................................................................................................... 921

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MPEG_CLOSE .............................................................................................................. 923MPEG_OPEN ................................................................................................................ 924MPEG_PUT ................................................................................................................... 928MPEG_SAVE ................................................................................................................ 930MSG_CAT_CLOSE ...................................................................................................... 931MSG_CAT_COMPILE ................................................................................................. 932MSG_CAT_OPEN ........................................................................................................ 934MULTI ........................................................................................................................... 936N_ELEMENTS .............................................................................................................. 937N_PARAMS .................................................................................................................. 938N_TAGS ........................................................................................................................ 939NCDF_* Routines .......................................................................................................... 940NEWTON ...................................................................................................................... 941NORM ............................................................................................................................ 944OBJ_CLASS .................................................................................................................. 946OBJ_DESTROY ............................................................................................................ 947OBJ_ISA ........................................................................................................................ 948OBJ_NEW ..................................................................................................................... 949OBJ_VALID .................................................................................................................. 951OBJARR ........................................................................................................................ 953ON_ERROR .................................................................................................................. 954ON_IOERROR .............................................................................................................. 955ONLINE_HELP ............................................................................................................. 956OPEN ............................................................................................................................. 959

Note On IEEE to VAX Format Conversion ............................................................ 969OPLOT ........................................................................................................................... 971OPLOTERR ................................................................................................................... 974P_CORRELATE ............................................................................................................ 975PARTICLE_TRACE ..................................................................................................... 977PCOMP .......................................................................................................................... 979PLOT .............................................................................................................................. 983PLOT_3DBOX .............................................................................................................. 987PLOT_FIELD ................................................................................................................ 991PLOTERR ...................................................................................................................... 993PLOTS ........................................................................................................................... 994PNT_LINE ..................................................................................................................... 997

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Contents IDL Reference Guide

POINT_LUN ................................................................................................................. 999Use Of POINT_LUN On Compressed Files ........................................................... 999

POLAR_CONTOUR ................................................................................................... 1001POLAR_SURFACE .................................................................................................... 1003POLY ........................................................................................................................... 1005POLY_2D .................................................................................................................... 1006POLY_AREA .............................................................................................................. 1010POLY_FIT ................................................................................................................... 1011POLYFILL .................................................................................................................. 1015

Fill Methods .......................................................................................................... 1015POLYFILLV ................................................................................................................ 1019POLYSHADE .............................................................................................................. 1021POLYWARP ............................................................................................................... 1025POPD ........................................................................................................................... 1027POWELL ..................................................................................................................... 1028PRIMES ....................................................................................................................... 1031PRINT/PRINTF ........................................................................................................... 1032

Format Compatibility ............................................................................................ 1033PRINTD ....................................................................................................................... 1035PRO .............................................................................................................................. 1036PROFILE ..................................................................................................................... 1037PROFILER .................................................................................................................. 1039PROFILES ................................................................................................................... 1041

Using PROFILES .................................................................................................. 1041PROJECT_VOL .......................................................................................................... 1043PS_SHOW_FONTS .................................................................................................... 1046PSAFM ........................................................................................................................ 1047PSEUDO ...................................................................................................................... 1048PTR_FREE .................................................................................................................. 1050PTR_NEW ................................................................................................................... 1051PTR_VALID ................................................................................................................ 1052PTRARR ...................................................................................................................... 1054PUSHD ........................................................................................................................ 1055QROMB ....................................................................................................................... 1056QROMO ...................................................................................................................... 1058QSIMP ......................................................................................................................... 1061

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QUERY_* Routines ..................................................................................................... 1063QUERY_BMP ............................................................................................................. 1065QUERY_DICOM ........................................................................................................ 1066QUERY_IMAGE ......................................................................................................... 1068QUERY_JPEG ............................................................................................................. 1071QUERY_PICT ............................................................................................................. 1072QUERY_PNG .............................................................................................................. 1073QUERY_PPM .............................................................................................................. 1075QUERY_SRF ............................................................................................................... 1076QUERY_TIFF .............................................................................................................. 1077QUERY_WAV ............................................................................................................ 1079R_CORRELATE ......................................................................................................... 1080R_TEST ....................................................................................................................... 1082RADON ....................................................................................................................... 1084RANDOMN ................................................................................................................. 1093RANDOMU ................................................................................................................. 1098RANKS ........................................................................................................................ 1103RDPIX .......................................................................................................................... 1105

Using RDPIX ........................................................................................................ 1105READ/READF ............................................................................................................ 1106

Format Compatibility ............................................................................................ 1108READ_ASCII .............................................................................................................. 1109READ_BINARY ......................................................................................................... 1112READ_BMP ................................................................................................................ 1114READ_DICOM ........................................................................................................... 1116READ_IMAGE ............................................................................................................ 1117READ_INTERFILE .................................................................................................... 1119READ_JPEG ................................................................................................................ 1120READ_PICT ................................................................................................................ 1124READ_PNG ................................................................................................................. 1126READ_PPM ................................................................................................................. 1129READ_SPR ................................................................................................................. 1131READ_SRF ................................................................................................................. 1132READ_SYLK .............................................................................................................. 1134READ_TIFF ................................................................................................................ 1137READ_WAV ............................................................................................................... 1144

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READ_WAVE ............................................................................................................ 1145READ_X11_BITMAP ................................................................................................ 1147READ_XWD ............................................................................................................... 1149READS ........................................................................................................................ 1150READU ........................................................................................................................ 1152REBIN ......................................................................................................................... 1155

Rules Used by REBIN .......................................................................................... 1155Endpoint Effects When Expanding ....................................................................... 1156

RECALL_COMMANDS ............................................................................................ 1158RECON3 ...................................................................................................................... 1159

Using RECON3 ..................................................................................................... 1159REDUCE_COLORS .................................................................................................... 1164REFORM ..................................................................................................................... 1165REGRESS .................................................................................................................... 1167REPEAT...UNTIL ....................................................................................................... 1171REPLICATE ................................................................................................................ 1172REPLICATE_INPLACE ............................................................................................. 1173RESOLVE_ALL .......................................................................................................... 1175RESOLVE_ROUTINE ................................................................................................ 1177RESTORE .................................................................................................................... 1179

Note to VMS Users ............................................................................................... 1179RETALL ...................................................................................................................... 1181RETURN ..................................................................................................................... 1182REVERSE .................................................................................................................... 1184REWIND ..................................................................................................................... 1186RK4 .............................................................................................................................. 1187ROBERTS ................................................................................................................... 1189ROT ............................................................................................................................. 1191ROTATE ...................................................................................................................... 1194ROUND ....................................................................................................................... 1196ROUTINE_INFO ........................................................................................................ 1198RS_TEST ..................................................................................................................... 1201S_TEST ........................................................................................................................ 1203SAVE ........................................................................................................................... 1205SAVGOL ..................................................................................................................... 1208SCALE3 ....................................................................................................................... 1212

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SCALE3D .................................................................................................................... 1214SEARCH2D ................................................................................................................. 1215SEARCH3D ................................................................................................................. 1218SET_PLOT .................................................................................................................. 1221SET_SHADING .......................................................................................................... 1223SET_SYMBOL ............................................................................................................ 1225SETENV ...................................................................................................................... 1226SETLOG ...................................................................................................................... 1227SETUP_KEYS ............................................................................................................. 1229SFIT ............................................................................................................................. 1232SHADE_SURF ............................................................................................................ 1234

Restrictions ............................................................................................................ 1234SHADE_SURF_IRR ................................................................................................... 1239SHADE_VOLUME ..................................................................................................... 1241SHIFT .......................................................................................................................... 1244SHOW3 ........................................................................................................................ 1246SHOWFONT ............................................................................................................... 1248SIN ............................................................................................................................... 1250SINDGEN .................................................................................................................... 1251SINH ............................................................................................................................ 1252SIZE ............................................................................................................................. 1253

IDL Type Codes .................................................................................................... 1253SKEWNESS ................................................................................................................ 1257SKIPF ........................................................................................................................... 1258SLICER3 ...................................................................................................................... 1259

The SLICER3 Graphical User Interface ............................................................... 1260Operational Details ................................................................................................ 1273

SLIDE_IMAGE ........................................................................................................... 1277SMOOTH ..................................................................................................................... 1281SOBEL ......................................................................................................................... 1283SOCKET ...................................................................................................................... 1285SORT ........................................................................................................................... 1289SPAWN ........................................................................................................................ 1291SPH_4PNT ................................................................................................................... 1298SPH_SCAT .................................................................................................................. 1300SPHER_HARM ........................................................................................................... 1303

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Contents IDL Reference Guide

SPL_INIT .................................................................................................................... 1306SPL_INTERP .............................................................................................................. 1308SPLINE ........................................................................................................................ 1310SPLINE_P .................................................................................................................... 1312SPRSAB ...................................................................................................................... 1314SPRSAX ...................................................................................................................... 1316SPRSIN ........................................................................................................................ 1318SPRSTP ....................................................................................................................... 1321SQRT ........................................................................................................................... 1322STANDARDIZE ......................................................................................................... 1323STDDEV ...................................................................................................................... 1325STOP ............................................................................................................................ 1326STRARR ...................................................................................................................... 1327STRCMP ...................................................................................................................... 1328STRCOMPRESS ......................................................................................................... 1330STREAMLINE ............................................................................................................ 1331STREGEX ................................................................................................................... 1333STRETCH .................................................................................................................... 1337STRING ....................................................................................................................... 1339

Differences Between STRING and PRINT .......................................................... 1340STRJOIN ..................................................................................................................... 1342STRLEN ...................................................................................................................... 1343STRLOWCASE ........................................................................................................... 1344STRMATCH ................................................................................................................ 1345STRMESSAGE ........................................................................................................... 1348STRMID ...................................................................................................................... 1349STRPOS ....................................................................................................................... 1351STRPUT ...................................................................................................................... 1353STRSPLIT ................................................................................................................... 1355STRTRIM .................................................................................................................... 1359STRUCT_ASSIGN ...................................................................................................... 1361STRUCT_HIDE .......................................................................................................... 1363STRUPCASE ............................................................................................................... 1365SURFACE ................................................................................................................... 1366

Restrictions ............................................................................................................ 1366SURFR ......................................................................................................................... 1371

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IDL Reference Guide Contents

SVDC ........................................................................................................................... 1372SVDFIT ........................................................................................................................ 1375SVSOL ......................................................................................................................... 1380SWAP_ENDIAN ......................................................................................................... 1382SWITCH ...................................................................................................................... 1383SYSTIME .................................................................................................................... 1385T_CVF ......................................................................................................................... 1388T_PDF .......................................................................................................................... 1389T3D .............................................................................................................................. 1391TAG_NAMES ............................................................................................................. 1394TAN ............................................................................................................................. 1396TANH .......................................................................................................................... 1397TAPRD ........................................................................................................................ 1398TAPWRT ..................................................................................................................... 1399TEK_COLOR .............................................................................................................. 1400TEMPORARY ............................................................................................................. 1401TETRA_CLIP .............................................................................................................. 1402TETRA_SURFACE ..................................................................................................... 1404TETRA_VOLUME ...................................................................................................... 1405THIN ............................................................................................................................ 1407THREED ...................................................................................................................... 1409TIME_TEST2 .............................................................................................................. 1410TIMEGEN .................................................................................................................... 1411TM_TEST .................................................................................................................... 1416TOTAL ........................................................................................................................ 1418TRACE ........................................................................................................................ 1421TrackBall Object .......................................................................................................... 1422TRANSPOSE ............................................................................................................... 1423TRI_SURF ................................................................................................................... 1425TRIANGULATE ......................................................................................................... 1429TRIGRID ..................................................................................................................... 1432TRIQL .......................................................................................................................... 1440TRIRED ....................................................................................................................... 1442TRISOL ........................................................................................................................ 1443TRNLOG ..................................................................................................................... 1445TS_COEF ..................................................................................................................... 1447

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Contents IDL Reference Guide

TS_DIFF ...................................................................................................................... 1449TS_FCAST .................................................................................................................. 1451TS_SMOOTH .............................................................................................................. 1453TV ................................................................................................................................ 1455TVCRS ........................................................................................................................ 1459TVLCT ........................................................................................................................ 1461TVRD .......................................................................................................................... 1464

Unexpected Results Using TVRD with X Windows ............................................ 1465TVSCL ......................................................................................................................... 1467UINDGEN ................................................................................................................... 1469UINT ............................................................................................................................ 1470UINTARR .................................................................................................................... 1471UL64INDGEN ............................................................................................................. 1472ULINDGEN ................................................................................................................. 1473ULON64ARR .............................................................................................................. 1474ULONARR ...........................................................................................