Re^2: Algorithm for cancelling common factors between two lists of multiplicands

There are better ways to compute factorial quotients without overflow or loss of precision.

So, now I've got my "schoolboy approach" working, care to point me at the methods clever people would use?

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?

"Science is about questioning the status quo. Questioning authority".

The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.

Comment on Re^2: Algorithm for cancelling common factors between two lists of multiplicands

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Re^3: Algorithm for cancelling common factors between two lists of multiplicands
by QM (Parson) on Aug 09, 2005 at 15:19 UTC

So, now I've got my "schoolboy approach" working, care to point me at the methods clever people would use?

In QOTW #2 MJD considers the n_choose_k function that computes:

sub n_choose_k {
  my ($n, $k) = @_;
  # f($n) = $n!
  return f($n)/f($k)/f($n-$k);
}
[download]

sub n_choose_k {
  my ($n, $k) = @_;
  my $t = 1;
  for my $i (1 .. $k) {
    $t *= $n - $k + $i;
    $t /= $i;
  }
  return $t;
}
[download]

$t here is always an integer, and never gets bigger than necessary.

-QM
--
Quantum Mechanics: The dreams stuff is made of

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