Matlab vs. Scilab

Rafael Brunner

What‘s going on?• Few words about Scilab‘s origin• Introduction to Scilab:

- linear algebra- programming

• Parts of my term work:- sparse matrices- Savitzky-Golay filter- performance comparison

• My own experiences

Scilab• developed since 1990 at INRIA /

ENPC (France)• open source• free of charge• high quality toolboxes available

- artificial network- serial port

• similar to Matlab... yes, but...

Demo• Linear Algebra

- basics (how to enter matrices etc.)- compute with matrices- solving systems of equations- hessenberg form- LU-, QR-decomposition- eigenvalues, -vectors- SVD

Programming• introduction / overview• example: poisson2d_kron

Overview (1)• for var = expr, statement; ...;

statement; end• while expression, statements; end• if expr then statements;

elseif expr then statements;else statements;end

Overview (2)• select expr

case expr1 then instructions1 ... case exprn then instructionsn [else instructions]end

Overview (3)• [lhs,rhs] = argn(0)• error• warning

Example (demo)• poisson2d_kron.m poisson2d_kron.sci• mfile2sci

2D-Poisson matrix

Sparse matrices• Three different algorithms to

generate the 2D-Poisson matrix:- set the elements one by one- block wise- kronecker product

Performance comparison

Solving a system Ax=b• in this case Ax = 1• pcg (preconditioned conjugate

gradients method)• Scilab does not provide a pcg

method Scilin (IRISA)

Demo• Solving Ax=1 for n=100• 2D-Poisson matrix generated by

poisson2d_kron

Performance comparison

Savitzky-Golay Filter• measured data (slowly varying and

corrupted by random noise)• reconstruction of the underlying

smooth function

Savitzky-Golay Filter (DEMO)

My own experiences• editor• translating

- build up new functions- mfile2sci

Summary• speed• graphics• signal processing

Is Scilab an alternative to Matlab?

In my opinion:Scilab is capable and can be

an alternative to Matlab.