You are using strict, right?

Add a 'use Data::Dumper' at the top and dump the hash with 'print Dumper(\%angles)' just before the sort. This should tell you what's in the hash.

The lines

006  $pdl1 = pdl (@{$matrix}[0]);
...
009      $pdl2 = pdl (@{$matrix}[$j]);
[download]

If $matrix is a 2-d array reference, you probably want to dereference that as $matrix->[0]. PDL likes array references just fine for initializing piddles.

After Compline,
Zaxo

It all looks pretty sane to me with seeing the data. I would suggest the you include a print statement in the sort block and see what you are getting.

my @sorted = sort {
    print "$a|$b|$angles{$a}|$angles{$b}\n";
    $angles{$a} <=> $angles{$b}
} keys %angles;
[download]

I just did what you said, and keys '33' and '32' print with their values. But their values are just random numbers in my hash. My question now is, can anyone see anything in my calculations that would have screwed up the values? Does PDL return values that can't be sorted?

You may need to re-evaluate where your error is coming from.. this runs fine on perl 5.8

my %hash = (
        key1 => 1,
        key2 => 2,
        key3 => 3,
        empty => undef,
        string => 'blah',
        string2 => '4',
       );

my @sorted = sort {$hash{$a} <=> $hash{$b}} keys %hash;

print "\nSorted:\n";
foreach(@sorted){ print "$_\n"; }

__END__

prints:

Sorted:
string
empty
key1
key2
key3
string2
[download]

cheers,

J

Try this:

use Math::Cephes qw/acos/;
for ( -2, -1.1, -1, 0, 1, 1.1, 2 ) {
  print acos($_),$/;
}
[download]

I expect you are getting something similar (i.e. #QNAN), as I am guessing some of the values $d are outside the domain of the "Real" solutions of acos.

-enlil

Can't acos return undef (for invalid input)?

--
I'm not belgian but I play one on TV.

Just a thought, but is $dotproduct a PDL? If so, using acos should screw things up. But it's been a while since I used PDL.