Math::Matrix anyone? (GeoBoater)

Math::Matrix anyone?

GeoBoater

created: 2006-08-02 14:05:07

perlmonks

node
author

prlmnks

node
author

Oh wisest perl monks,

I'm trying to do some oh-so-simple matrix calculations with Math::Matrix, but the usage of the major functions (cross_product, dot_product, etc) are poorly documented on CPAN, so I'm not sure if I'm even calling them properly.
http://search.cpan.org/~ulpfr/Math-Matrix-0.5/Matrix.pm

Most other functions work, such as print, transpose, etc, but none of the more useful algorithms return anything.

Does anyone have any experience with this? Am I even asking in the right forum?

Here's what I've tried so far:

#! /usr/bin/perl

        use Math::Matrix;

        $a = new Math::Matrix ([1], [2], [3]);
        $x = new Math::Matrix ([4], [5], [6]);

        $a->print("A\n");
        $x->print("X\n");

        $f = $a->cross_product( $x );
        print "output of a->cross_product( x ) is: '$f'\n\n";
        if( defined( $f ) ) { $f->print( "Cross product is \n" ) };

        $f = $a->cross_product( $a, $x );
        print "output of a->cross_product( a, x ) is: '$f'\n\n";
        if( defined( $f ) ) { $f->print( "Cross product is \n" ) };

Script outputs:

$ mathtest.pl 
A
   1.00000 
   2.00000 
   3.00000 
X
   4.00000 
   5.00000 
   6.00000 
output of a->cross_product( x ) is: ''

output of a->cross_product( a, x ) is: ''

Any help would be much appreciated. Thanks!!

Ryan

Re: Math::Matrix anyone?

dirving

created: 2006-08-02 14:48:47

perlmonks

prlmnks

I'm not sure about that particular module, but if you can't get it to work you might want to try PDL, which is very well documented and supported although it contains a lot of extra functionality you might not need. In particular check PDL::Primitive for the cross and dot product functions after you've read PDL::Impatient so you understand the basics.

Re: Math::Matrix anyone?

zentara

created: 2006-08-02 15:48:16

perlmonks

prlmnks

I think [cpan://Math-VectorReal] will work better for you.

#!/usr/bin/perl
use warnings;
use strict;
use Math::VectorReal;

my $a = vector( 1, 2, 3 );
my $b = vector( 4, 5, 6 );

print "Vector as string (MatrixReal default format)\n\$a => ", $a;
print $a->stringify( "Formated Output   \$a => { %g, %g, %g }\n" );

print "Vector as string (MatrixReal default format)\n\$b => ", $b;
print $b->stringify( "Formated Output   \$b => { %g, %g, %g }\n" );

print 'dot product $a . $b =', $a . $b, "\n\n";
print 'cross product $a x $b =', $a x $b, "\n\n";

I'm not really a human, but I play one on earth. Cogito ergo sum a bum

Re^2: Math::Matrix anyone?

GeoBoater

created: 2006-08-02 17:10:55

perlmonks

prlmnks

Thanks. I'll give that a try!

Ryan

Re: Math::Matrix anyone? (source)

tye

created: 2006-08-02 16:43:15

perlmonks

prlmnks

You do realize that you have full access to the source code, right?

sub cross_product {
  my $vectors = shift;
  my $class = ref($vectors);

  my $dimensions = @{$vectors->[0]};
  return undef
    unless $dimensions == @$vectors + 1;

indicates that cross_product() expects to receive a single (blessed) matrix that contains the vectors to be ~~productized~~multiplied.

I'm not saying that this access excuses unclear documentation, of course. But I suspect you can use the source to answer your own questions faster then you'll get answers from someone else. Producing a patch for the module might be a good result of your investigation.

- [tye]

Re^2: Math::Matrix anyone? (source)

GeoBoater

created: 2006-08-02 17:21:19

perlmonks

prlmnks

I know, I know. I gave the source code a quick look, didn't quite understand all of what it was doing (being a lowly noobie perl programmer) and begged for help here. Maybe if I have time I'll go back and play around with it.

Thanks.

Ryan