shell中的数学运算

wrl

格式为：

$echo $((sqrt(2)))
1.41421356237309505
$

ksh中函数有：
abs acos acosh asin asinh atan atan2 atanh cbrt copysign cos cosh erf  erfc  exp  exp2  expm1  fabs  fdim
finite  floor  fma fmax fmod hypot ilogb int isinf isnan lgamma log log2 logb nearbyint nextafter nexttoward
pow remainder rint round sin sinh sqrt tan tanh tgamma trunc

每一个函数的用法都可以通过man的方式获得，如

$man nexttoward

       The nextafter() functions return the next representable neighbor of x in the direction  towards  y.   The
       size  of the step between x and the result depends on the type of the result.  If x = y the function sim-
       ply returns y.  If either value is NaN, then NaN is returned.  Otherwise a  value  corresponding  to  the
       value of the least significant bit in the mantissa is added or subtracted, depending on the direction.

       The  nexttoward() functions do the same as the nextafter() functions, except that they have a long double
       second argument.

......

haimming

谢lz教导