numeric.c:576
static VALUE
flo_cmp(x, y)
    VALUE x, y;
{
    double a, b;

    a = RFLOAT(x)->value;
    switch (TYPE(y)) {
      case T_FIXNUM:
	b = (double)FIX2LONG(y);
	break;

      case T_BIGNUM:
	b = rb_big2dbl(y);
	break;

      case T_FLOAT:
	b = RFLOAT(y)->value;
	break;

      default:
	return rb_num_coerce_cmp(x, y);
    }
    return rb_dbl_cmp(a, b);
}
