modulo

static VALUE
flo_mod(VALUE x, VALUE y)
{
    double fy, mod;

    switch (TYPE(y)) {
      case T_FIXNUM:
        fy = (double)FIX2LONG(y);
        break;
      case T_BIGNUM:
        fy = rb_big2dbl(y);
        break;
      case T_FLOAT:
        fy = RFLOAT_VALUE(y);
        break;
      default:
        return rb_num_coerce_bin(x, y, '%');
    }
    flodivmod(RFLOAT_VALUE(x), fy, 0, &mod);
    return DBL2NUM(mod);
}