#! perl
use strict;
use warnings;
use Data::Dump;

my @matrix;
my $row = 0;
push @{$matrix[$row++]}, split while <DATA>;
dd @matrix;
print 'element at col 3, row 2 is ', get_element(\@matrix, 3, 2), "\n";

sub get_element
{
    my ($matrix_ref, $col, $row) = @_;
    return $matrix_ref->[$row - 1][$col - 1];
}

__DATA__
20 30 40
60 70 80
90 100 49

##</code><code>##

23:50 >perl 548_SoPW.pl
([20, 30, 40], [60, 70, 80], [90, 100, 49])
element at col 3, row 2 is 80

23:50 >

##</code><code>##

my   @matrix;
push @matrix, [ split ] while <DATA>;