Matlab vs. Scilab

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Matlab vs. Scilab

• Rafael Brunner

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Whats going on?

• Few words about Scilabs origin
• Introduction to Scilab- linear algebra-
  programming
• Parts of my term work- sparse matrices-
  Savitzky-Golay filter- performance comparison
• My own experiences

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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...

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Demo

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

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Programming

• introduction / overview
• example poisson2d_kron

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Overview (1)

• for var expr, statement ... statement end
• while expression, statements end
• if expr then statementselseif expr then
  statementselse statementsend

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Overview (2)

• select expr case expr1 then instructions1
  ... case exprn then instructionsn else
  instructionsend

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Overview (3)

• lhs,rhs argn(0)
• error
• warning

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Example (demo)

• poisson2d_kron.m ? poisson2d_kron.sci
• mfile2sci

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2D-Poisson matrix
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Sparse matrices

• Three different algorithms to generate the
  2D-Poisson matrix- set the elements one by
  one- block wise- kronecker product

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Performance comparison
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Solving a system Axb

• in this case Ax 1
• pcg (preconditioned conjugate gradients method)
• Scilab does not provide a pcg method ? Scilin
  (IRISA)

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Demo

• Solving Ax1 for n100
• 2D-Poisson matrix generated by poisson2d_kron

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Performance comparison
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Savitzky-Golay Filter

• measured data (slowly varying and corrupted by
  random noise)
• reconstruction of the underlying smooth function

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Savitzky-Golay Filter (DEMO)
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My own experiences

• editor
• translating- build up new functions- mfile2sci

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Summary

• speed
• graphics
• signal processing

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Is Scilab an alternative to Matlab?
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In my opinionScilab is capable and can be an
alternative to Matlab.