sub makeRatio { 
    my( $d_h ) = @_;
    my $rows    =  $#$d_h ; ## last index of array
    my $columns =  $#{ $d_h->[0] }; ## last index of first row
    my @ratio;
    for my $six ( 0 .. $columns ){
        for my $tre ( 0 .. $rows ){
            for my $tri ( 0 .. $rows ){
                ## for visual matching
                printf 'my $ratio%d_%d_%d  = $$d_h[%d][%d] / $$d_h[%d][%d];'."\n",
                    1+$six, 1+$tri, 1+$tre,
                    $tri, $six,
                    $tre, $six,
                    ;;;
                $ratio[ $six ][ $tri ][ $tre ] = $$d_h[ $tri ][ $six ] / $$d_h[ $tre ][ $six ] ;
            }
        }
    }
    return \@ratio ;
}