计算圆周率 Pi (π)值, 精确到小数点后 10000 位 只需要 30 多句代码！-Pi calculated pi () values, accurate to 10,000 decimal places only need more than 30 sentence code!

高效的数值算法，使用普通精度计算圆周率。不需要高精度的支持-Efficient numerical algorithm, calculation of pi using ordinary precision. Does not require the support of high-precision