retroforth/example/least-common-multiple.retro

# Least Common Multiple

The least common multiple of two integers a and b, is the
smallest positive integer that is divisible by both a and b.

This implements a word to find this in RETRO.

It uses a formula that reduces the problem to computing the
greatest common divisor (gcd), as in:

    lcm(a,b) = |a*b| / gcd(a,b)

~~~
:gcd (ab-n)
  [ tuck mod dup ] while drop ;

:lcm (ab-n)
  dup-pair gcd [ * ] dip / ;
~~~