Re: Dot product of three matrices

a few comments:

why not use an existing solution? quick cpan search found Math::Matrix that has (among other things) a dot_product method.
Why are you storing arrays of the components (e.g. @x, @y, @z) instead of storing the vectors, for example:
```
my @vector1 = ( 2, -4, 2 );
my @vector2 = ( 5, -3, -6);
[download]
```
Obviously the logic is the same, but using vectors is much clearer code-wise and mathematically.
use strict; and use warnings;

shouldn't the length check include ct3?

      return unless $ct1 && $ct1 == $ct2 && $ct2 == $ct3;
[download]

Simply doing my $ct1 = scalar @$x; might be clearer that adding to $#

one (of many possible) more "perl-ish" solutions:

      my $sum = 0;
      foreach my $i ( 0 .. $#$x ){
        $sum += $x->[$i] * $y->[$i] * $z->[$i];
      }
      return $sum;
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Another:

  my $sum = 0;
  $sum += $x->[$_] * $y->[$_] * $z->[$_] for 0 .. $#$x;
  return $sum;
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Re^2: Dot product of three matrices (wheels) by tye (Sage) on Aug 01, 2005 at 17:42 UTC
It is little enough code that writing it yourself is likely often much less time-consuming than finding an appropriate solution, much less getting that solution installed. But, I'd have implemented in terms of some useful abstractions that I personally keep at-hand: `use List::Util 'reduce'; use Algorithm::Loops 'MapCarE'; my $prod= reduce {$a+$b} MapCarE { reduce {$a*$b} @_ } \( @x, @y, @z ) +;` [download] - tye	[reply] [d/l]

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Re^2: Dot product of three matrices (wheels)
by tye (Sage) on Aug 01, 2005 at 17:42 UTC

It is little enough code that writing it yourself is likely often much less time-consuming than finding an appropriate solution, much less getting that solution installed. But, I'd have implemented in terms of some useful abstractions that I personally keep at-hand:

use List::Util 'reduce';
use Algorithm::Loops 'MapCarE';

my $prod= reduce {$a+$b} MapCarE { reduce {$a*$b} @_ } \( @x, @y, @z )
+;
[download]

- tye

[reply]
[d/l]