寻找大量的立方根

Question

我需要找到向上四舍五入的巨大(5k位左右)数字的立方根.我怎么做？

Answer 1

如果GNU bc适合你,这可能会:

http://phodd.net/gnu-bc/bcfaq.html#bccbrt

编辑:

它基本归结为:

$ bc -l
define cbrt(x) { return e(l(x)/3) }

您需要增加scale变量才能获得必要的精度:

$ bc -l
bc 1.06.95
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.

define cbrt(x) { return e(l(x)/3) }

cbrt(10000000000000000000000000000000000000000000000000000000000000000000)^3
9999999999999999999845725361475980907263179272258247094885777761435.\
89049462743995306310

scale=1000

cbrt(10000000000000000000000000000000000000000000000000000000000000000000)^3
9999999999999999999999999999999999999999999999999999999999999999999.\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999999999999999999999999\
99999999999999999999999999999999999999999999999978254573198390239858\
069738839057154871628814670160708326688382280410

正如您可能已经注意到的那样,在不增加scale变量的情况下(在我的系统上它默认为20),结果远不及您所需的精度.