greatest common factor

[MrNobo1024]

These functions determine the greatest common factor or least common multiple of a set of numbers. gcf() and lcm() take two numbers as arguments, and multigcf() and multilcm() will take any amount. EDIT: fixed a bug in multigcf().

sub gcf {
  my ($x, $y) = @_;
  ($x, $y) = ($y, $x % $y) while $y;
  return $x;
}

sub lcm {
  return($_[0] * $_[1] / gcf($_[0], $_[1]));
}

sub multigcf {
  my $x = shift;
  $x = gcf($x, shift) while @_;
  return $x;
}

sub multilcm {
  my $x = shift;
  $x = lcm($x, shift) while @_;
  return $x;
}

[zeno]

Very elegantly done. BTW, there's a typo in the sub multigcf: gcd should be gcf! Otherwise, a very nice offering.
-zeno

sub multigcf {
  my $x = shift;
  $x = gcd($x, shift) while @_; #should be gcf!
  return $x;
}

[Anonymous Monk]

its greatest common divisor , hence gcd

[TheAmigo]

I found this function and it seemed reasonable, but some of my users reported that I was somtimes returning the wrong sign. Turns out that the function above has inconsistent behavior on negative numbers:

gcf(-5, 5) = 5
gcf(5, -5) = -5

when they should really both be 5.

14 years late, but here's a fix. I changed my code so that gcf() ends with

return abs $x;

[Anonymous Monk]

the copy/paste i needed

many thanks ^_^