function lcm( a, b ) {
	var d;
	if ( a === 0 || b === 0 ) {
		return 0;
	}
	if ( a < 0 ) {
		a = -a;
	}
	if ( b < 0 ) {
		b = -b;
	}
	// Note: we rely on `gcd` to perform further argument validation...
	d = gcd( a, b );
	if ( isnan( d ) ) {
		return d;
	}
	return (a/d) * b;
}
Computes the least common multiple (lcm).

@param {integer} a - integer
@param {integer} b - integer
@returns {integer} least common multiple

@example
var v = lcm( 21, 6 );
// returns 42

@example
var v = lcm( 3.14, 6 );
// returns NaN

@example
var v = lcm( NaN, 6 );
// returns NaN