#!/usr/bin/perl

use strict;

package ary;

 use Math::Matrix;
 @ary::ISA = qw(Math::Matrix);
 use overload '+' => \&aryadd;
 sub aryadd {
   return $_[0]->add($_[1]);
 };

package main;

 my( %totals, %delta );
 my @fields = qw/foo bar bat/;
 @totals{ @fields } = ( 10, 20, 30 );
 @delta{ @fields } = ( 5, 6, 1 );

 my $t = new ary([@totals{ @fields }]);
 my $d = new ary([@delta{ @fields }]);

 $t += $d;   # this works too:
             # $t = $t->add($d);
             # $t = $t + $d;

 $t->print("Totals:\n");

 # this works too:
 # my $aref = $t->[0]; print "> $_\n" foreach (@$aref);