void
_do_matrix( char *in, long rows, long cols, char *out )
CODE:
  long i, j, a;
  double *in_matrix= (double *)in;
  double *out_matrix= (double *)out;
  double value;

  for(  i= 0;  i < rows;  i++  ) {
    for(  j= i-1;  j >= 0;  j--  ) {
      value= 0;
      for(  a= 0;  a <= cols;  a++  ) {
        value += in_matri­x[i*cols+a]*in_matrix[j*cols+a];
      }
      value /= (cols-1);
      out_matrix[i*rows+j]= val­ue;
    }
  }

##</code><code>##

sub do_matrix(\@) {
    my( $avMatrix )= @_;
    my( $rows )= 0+@$avMatrix;
    my( $cols )= 0+@{$avMatrix->[0]};
    my $in= pack "d*", map @$_[0..$cols-1], @$avMatrix;
    my $out= pack "d".($rows*$rows);
    _do_matrix( $in, $rows, $cols, $out );
    my @out= unpack "d*", $out;
    my @ret;
    while(  @out  ) {
        push @ret, [ splice( @out, 0, $rows ) ];
    }
    return \@ret;
}