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.