public static RatNum make(IntNum num, IntNum den)
{
IntNum g = IntNum.gcd (num, den);
if (den.isNegative ())
g = IntNum.neg (g);
if (! g.isOne ())
{
num = IntNum.quotient (num, g);
den = IntNum.quotient (den, g);
}
return den.isOne () ? (RatNum)num : (RatNum)(new IntFraction (num, den));
}