Here is a working example that demonstrates a bit more:

use strict;
use warnings;
use Data::Dumper;


my @matrix;
while (<DATA>){
    chomp;
    my @row = split;
    print "second item in row: $row[1]\n";
    push @matrix, \@row;
}

print "And this is how the matrix look like:\n";
print Dumper \@matrix;

print "Iterating over the matrix, getting the first column:\n";
for my $row (@matrix){
    print $row->[0], "\n";

}

__DATA__
-2.65 -2.0865e-006 2.0831e-006
-2.6 -2.0532e-006 2.0569e-006
-2.55 -2.0215e-006 2.0262e-006
[download]

If that doesn't help you, please show us the code you're using, and what you want it to print out.

See also perlreftut, perldata, perldsc.