my @m = (
[1, 1, 1, 1],
[2, 4, 8, 16],
[3, 9, 27, 81],
[4, 16, 64, 256],
[5, 25, 125, 625],
);
my @transposed;
foreach my $j (0..$#{$m[0]}) {
push(@transposed, [map $_->[$j], @m]);
}