ops me l'ero dimenticata:

codice:
# returns vector cross product of vectors p1p2 and p1p3
# using Cramer's rule
#
# args : reference to an array with 3 points p1,p2 and p3
#
sub CrossProduct {
  my $pointsref = $_[0];
  my @points = @$pointsref;
  if (@points != 3) {
    carp("Need 3 points for a cross product");
    return;
  }
  my @p1 = @{$points[0]};   <-linea 367
  my @p2 = @{$points[1]};
  my @p3 = @{$points[2]};
  my $det_p2p3 = &Determinant($p2[0], $p2[1], $p3[0], $p3[1]);
  my $det_p1p3 = &Determinant($p1[0], $p1[1], $p3[0], $p3[1]);
  my $det_p1p2 = &Determinant($p1[0], $p1[1], $p2[0], $p2[1]);
  return ($det_p2p3-$det_p1p3+$det_p1p2);
}