bc命令

bc 命令:
     bc 命令是用于命令行计算器。 它类似基本的计算器。 使用这个计算器可以做基本的数学运算。

[tough@localhost expr]$ echo *|bc

[tough@localhost expr]$ echo '8+2'|bc

[tough@localhost expr]$ echo "8 -2"|bc

把要计算工的内容放入文件中：

[tough@localhost expr]$ echo "4+5" > cal.txt

[tough@localhost expr]$ bc cal.txt
bc 1.06.
Copyright -, , , , ,  Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.

进入bc模式：

[tough@localhost expr]$ bc
bc 1.06.
Copyright -, , , , ,  Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.

+

 +

-

*

/

^

%

/

#设置精度
scale=

/
1.66

/
2.50

(^ - )/ +
26.00

quit

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

echo "scale=100; a(1)*4" | bc -l  （计算圆周率）