Linux系统下，可以用计算π的方法来简单评估CPU单核计算性能。

# 一、方法

```bash
[root@yz219 ~]# time echo "scale=5000; 4*a(1)" | bc -l -q
3.141592653589793238462643383279502884197169399375105820974944592307\
81640628620899862803482534211706798214808651328230664709384460955058\
22317253594081284811174502841027019385211055596446229489549303819644\
……

real	0m20.190s
user	0m20.126s
sys	0m0.082s
```

注：scale表示要计算到小数点后多少位。

## 1.1 MATH LIBRARY

If bc is invoked with the -l option, a math library is preloaded and the default  scale  is  set  to  20. 

The  math  functions  will  calculate their results to the scale set at the time of their call. 

The math library defines the following functions:

- s(x)  The sine of x, x is in radians.  正玄函数
- c(x)  The cosine of x, x is in radians.  余玄函数
- a(x)  The arctangent of x, arctangent returns radians. 反正切函数
- l(x)  The natural logarithm of x.  log函数(以2为底)
- e(x)  The exponential function of raising e to the value x.  e的指数函数
- j(n,x) The bessel function of integer order n of x.  贝塞尔函数

# 二、参考

- [计算圆周率](https://blog.csdn.net/zhuying_linux/article/details/7298465)
- [linux 测试cpu计算圆周率_linux下的CPU、内存、IO、网络的压力测试](https://blog.csdn.net/weixin_42502957/article/details/111972568)
- [Super PI](http://www.superpi.net/)