open (INM,"$in_matrix") or die "Unable to open 'in_matrix': $!";
my @row=split (/\t/,readline(INM));
my @colfiles=();
my $max=$#row;
foreach (0 .. $max) {
  open ($colfiles[$_],">$out_matrix.$_") or die "Failed on opening tempfile $_: $!";
  print {$colfiles[$_]} shift (@row);
}