脚本和浮点除法 [英] Division in script and floating-point

问题描述

我想在我的脚本中执行以下操作:

I would like to do the following operation in my script:

1 - ((m - 20) / 34)

我想将此操作的结果分配给另一个变量.我希望我的脚本使用浮点数学.例如，对于 m = 34:

I would like to assign the result of this operation to another variable. I want my script use floating point math. For example, for m = 34:

results = 1 - ((34 - 20) / 34) == 0.588

推荐答案

您可以使用 bc 计算器.如果您将 increease scale 从其默认值 0 设置为 0，它将使用小数(不是二进制浮点)进行任意精度的数学运算:

You could use the bc calculator. It will do arbitrary precision math using decimals (not binary floating point) if you set increease scale from its default of 0:

$ m=34
$ bc <<< "scale = 10; 1 - (($m - 20) / 34)"
.5882352942

-l 选项将加载标准数学库并将比例默认为 20:

The -l option will load the standard math library and default the scale to 20:

$ bc -l <<< "1 - (($m - 20) / 34)"
.58823529411764705883

然后您可以使用 printf 来格式化输出，如果您愿意的话:

You can then use printf to format the output, if you so choose:

printf "%.3f
" "$(bc -l ...)"

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