Thank you for identifying the problem with the variable i when using CGI and PDL simultaneously. I eliminated the CGI loads (and therefore was forced to run the PDL scripts from my shell - wish I could have it both ways). However, there is still a problem.

Let's suppose we want to solve two (2) complex simultaneous equations in two unknowns:

Equation 1: (1+i)*Xsub1 + (2+i)*Xsub2 = 5+10i

Equation 2: (1-2i)*Xsub1 + (2-i)*Xsub2 = 8 -5i

The following code using only real PDL variables, is well-behaved and correctly solves for the variables Xsub1 and Xsub2 as 3+i, and 2+i respectively as the execution demonstrated forthwith after the code prooves.

. 
#! /usr/bin/perl -w
use warnings;
use strict;    
use PDL;
my $matrixM = pdl  [ [ 1, 2,-1,-1],
                     [ 1, 2, 2, 1],
                     [ 1, 1, 1, 2],
                     [-2,-1, 1, 2] ];
my $matrixB = pdl [ [5],[10],
                    [8],[-5] ];
my $matrixX;
print "\$matrixM = ", $matrixM,"<br>\n";
print "\$matrixB = ", $matrixB,"<br>\n";
print "\$matrixX = ", $matrixM->inv x $matrixB,"<br>\n";
exit(0);

[download]
The results from running the above script are: 
$matrixM =
[ [ 1  2 -1 -1] 
 [ 1  2  2  1]
 [ 1  1  1  2]
 [-2 -1  1  2]]
$matrixB =
[ [ 5]
 [10]
 [ 8]
 [-5]]
$matrixX =
[ [         3] [         2]
  [         1] [         1]]

[download]
This says that Xsub1 = 3+i, and Xsub2 = 2+i .....which is the correct result!

Now, in an effort to simplify, let's use the following functionally equivalent (?) PDL with complex matrices to solve the same two same simultaneous equations; observe the results after the following code:

#! /usr/bin/perl -w
use warnings;
use strict;    
use PDL;
use PDL::Complex;
my $matrixM = pdl [ [ 1+1*i, 2+1*i], [ 1-2*i, 2-1*i] ];<br>
my $matrixB = pdl [ 5+8*i, 10-5*i ];
my $matrixX;
print "\$matrixM = ",$matrixM,"<br>\n";
print "\$matrixB = ", $matrixB,"<br>\n";
print "\$matrixX = ", $matrixM->inv x $matrixB,"<br>\n";
exit(0);

[download]
The results from running the above script are: 
$matrixM =[   [  [1 1] [2 1] ]    [ [ 1 -2] [ 2 -1] ]   ]
$matrixB =[  [ 5  8] [10 -5] ]
$matrixX =
[ [
  [  5 -13]
  [  0  21] ]
 [ [ 5 -6]
  [ 0 -7] ] ]

[download]
So my question is why am I getting such a clearly erroneous result when I run the second piece of code?

In reply to Re^2: PDL works for real number matrix operations, but not working for complex number matrix operations. by gmacfadden
in thread PDL works for real number matrix operations, but not working for complex number matrix operations. by gmacfadden

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.