examples/matrix/nonsymmetric_eigen_old

   1 #!/usr/bin/perl -w
   2 use Math::GSL          qw/:all/;
   3 use Math::GSL::Eigen   qw/:all/;
   4 use Math::GSL::Matrix  qw/:all/;
   5 use Math::GSL::Vector  qw/:all/;
   6 use Math::GSL::Complex qw/:all/;
   7 use Math::GSL::Errno qw/:all/;
   8 use Math::Complex;
   9 use Data::Dumper;
  10 use strict;
  11 my $matrix = Math::GSL::Matrix->new(2,2)
  12                               ->set_row(0, [0,-1] )
  13                               ->set_row(1, [1, 0] );
  14 print <<STUFF;
  15 Finding eigenvalue/eigenvectors for
  16 [ 0  -1 ]
  17 [ 1   0 ]
  18 STUFF
  19
  20 my $evec   = gsl_matrix_complex_alloc(2,2);
  21 my $eigen  = gsl_eigen_nonsymmv_alloc(2);
  22 my $vector = gsl_vector_complex_alloc(2);
  23
  24 # this actually computes the eigenvalues and vectors
  25 gsl_eigen_nonsymmv($matrix->raw,$vector, $evec, $eigen);
  26
  27 my $x = gsl_vector_complex_real($vector);
  28 my $y = gsl_vector_complex_imag($vector);
  29
  30 my $eig1 = as_complex( gsl_vector_get($x->{vector}, 0) ,  gsl_vector_get($y->{vector}, 0) );
  31 my $eig2 = as_complex( gsl_vector_get($x->{vector}, 1) ,  gsl_vector_get($y->{vector}, 1) );
  32
  33 my $u1 = as_complex( gsl_matrix_complex_get($evec, 0, 0) );
  34 my $u2 = as_complex( gsl_matrix_complex_get($evec, 1, 0) );
  35 my $v1 = as_complex( gsl_matrix_complex_get($evec, 0, 1) );
  36 my $v2 = as_complex( gsl_matrix_complex_get($evec, 1, 1) );
  37
  38 print <<ANSWER;
  39
  40 Eigenvectors:
  41
  42 u = ($u1,$u2)
  43 v = ($v1,$v2)
  44
  45 Eigenvalues:
  46
  47 lambda_0 = $eig1
  48 lambda_1 = $eig2
  49
  50 ANSWER
  51
  52 sub as_complex {
  53     my ($w,$v) = @_;
  54     my ($x,$y);
  55     if( ref $w ) {
  56         ($x,$y) = (gsl_real($w),gsl_imag($w));
  57     } else {
  58         ($x,$y) = ($w,$v);
  59     }
  60     my $z      = Math::Complex->make( $x, $y);
  61     return qq{$z};
  62 }