CSCI6370: Topics in Computer Science Advanced Topics in Algorithms and Applications Fall Semester, 2002

More stuff on plotting1Define x and y and call the plot function

2Engineers always add Title title(y = cos(x))X axis label, complete with units xlabel(x-axis)Y axis label, complete with units ylabel(y-axix)Often it is useful to add a grid grid onSingle quotes are used.3Change the line type in a plotExampleplot(x, y, ':ok')strings are identified with single quotesthe : means use a dotted linethe o means use a circle to mark each pointthe letter k indicates that the graph should be drawn in black(b indicates blue)

4Available choicesTable 5. 2 Line, Mark and Color OptionsLine TypeIndicatorPoint TypeIndicatorColorIndicatorsolid-point.bluebdotted:circleogreengdash-dot-.x-markxredrdashed--plus+cyancstar*magentamsquaresyellowydiamonddblackktriangle downvtriangle up^triangle left

pentagramphexagramh5

specify the drawing parameters for each line after the ordered pairs that define the line6SubplotsThe subplot command allows you to subdivide the graphing window into a grid of m rows and n columnssubplot(m,n,p)rowscolumnslocation7subplot(2,2,1)2 rows2 columns1234

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2 rows and 1 column9Other Types of 2-D PlotsPolar PlotsLogarithmic PlotsBar GraphsPie ChartsHistogramsX-Y graphs with 2 y axesFunction Plots10

Three Dimensional Plotting3D Line plots (i.e. plot3(x,y,z))Surface plots (i.e. mesh(z) and surf(z))Contour plots11

Mesh plotsmesh(z) plots out a 3D plot The z-axis are the values of zThe x-axis is each point corresponding to a columnThe y-axis is each point corresponding to a rowExample:

Z = [1 2 3; 4 5 6]mesh(Z)

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Mesh plots continuedCan also do mesh(x,y,z) this allows the x and y axis to be something else other than the number of rows and columnsx and y need to have the same dimensions as z.If x and y are vectors, need to use meshgrid to make them a 2D matrix. 13

meshgrid exampleExample:

Z = [1 2 3; 4 5 6] %2x3 matrixx=[0:3:6] %number of columns is 3y=[0:6:6] %number of rows is 2[X,Y] = meshgrid(x,y) %new X and Y that are 2x3 matricesmesh(X,Y,Z)xlabel(X)ylabel(Y)zlabel(Z)14

meshgrid example outputZ =

1 2 3 4 5 6

x =

0 3 6

y =

0 6

X =

0 3 6 0 3 6

Y =

0 0 0 6 6 6

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surf plotsA surf plot is basically the same as mesh plot except that surf plots give a color surface instead of a mesh

Ex: surf(X,Y,Z)16In-class assignmentProblems 4.6, 4.7, and 4.9 from the Matlab book17