numeric.c:389
static VALUE
flo_div(x, y)
    VALUE x, y;
{
    long f_y;
    double d;

    switch (TYPE(y)) {
      case T_FIXNUM:
	f_y = FIX2LONG(y);
	return rb_float_new(RFLOAT(x)->value / (double)f_y);
      case T_BIGNUM:
	d = rb_big2dbl(y);
	return rb_float_new(RFLOAT(x)->value / d);
      case T_FLOAT:
	return rb_float_new(RFLOAT(x)->value / RFLOAT(y)->value);
      default:
	return rb_num_coerce_bin(x, y);
    }
}
