for my $i (0 .. $#data) {
    for my $j (0 .. $#data) {

    next if $i == $j;

    my @coords_i = @{$data[$i]}[1,2,3];
    my @coords_j = @{$data[$j]}[1,2,3];

    print OUT "%s to %s Distance-%.5f\n",     ####( ; )??
        $data[$i][1], $data[$j][1],
        $data[$i][11], $data[$j][11],
        distance(\@coords_i, \@coords_j);
    }
    }