R中的大功率
我试着计算2**1000，并把数字的值加起来。对于所有的意图和目的，似乎我有正确的方法，但错误的答案，我不确定是否有一个特殊的方法来计算，或者我的选择可能是混乱的。
在任何情况下，R中的2**1000表示: 1.072e+301。我用过
options("scipen"=400, "digits"=4)为了去掉科学符号(因为我们想要数字)，这给了我：
10715086071862673211222842640062602864002646240220400600628246062604626466468802860684246408802204448642628020644428680866666080884644840024840004280840848880462604626804200880464480884860464420284266864402822668802420668620402620400466086288824662642224206428624064400880244462828666486484022626226666所以，我做了一件天真的事情，对这些数字做了一个和()：
sum(1,0,7,1,5,0...)但我得出的答案是1200，这是不正确的。我想不出和函数是怎么回事的，所以我假设选项把指数结果搞砸了？
回答 3
Stack Overflow用户
发布于 2014-03-11 08:32:10
您可以使用gmp库来处理大整数：
library(gmp)
bigNum <- as.bigz(2)^1000
# Now we want to split into characters so we can sum the numbers:
chars <- as.integer(strsplit(as.character(bigNum), "")[[1]])
sum(chars)
# 1366Stack Overflow用户
发布于 2014-03-11 07:39:44
为了计算2**1000，您必须使用BigInteger等效。
http://cran.at.r-project.org/web/packages/Brobdingnag/index.html
正确的答案是
2**1000 =
10715086071862673209484250490600018105614048117055336074437503883703510511249361224931983788156958581275946729175531468251871452856923140435984577574698574803934567774824230985421074605062371141877954182153046474983581941267398767559165543946077062914571196477686542167660429831652624386837205668069376
数字之和为1366
Stack Overflow用户
发布于 2014-03-11 08:09:54
或者，这里有另一种获得正确答案的方法(诀窍是将大整数作为字符串来进行数字拆分)：
options("scipen"=400, "digits"=4)
a <- 2^1000
a
[1] 10715086071862673209484250490600018105614048117055336074437503883703510511249361224931983788156958581275946729175531468251871452856923140435984577574698574803934567774824230985421074605062371141877954182153046474983581941267398767559165543946077062914571196477686542167660429831652624386837205668069376
b <- strsplit(as.character(a),"")[[1]]
b
[1] "1" "0" "7" "1" "5" "0" "8" "6" "0" "7" "1" "8" "6" "2" "6" "7" "3" "2" "0" "9" "4" "8" "4" "2" "5" "0" "4" "9" "0" "6" "0" "0" "0" "1" "8" "1" "0" "5" "6" "1"
[41] "4" "0" "4" "8" "1" "1" "7" "0" "5" "5" "3" "3" "6" "0" "7" "4" "4" "3" "7" "5" "0" "3" "8" "8" "3" "7" "0" "3" "5" "1" "0" "5" "1" "1" "2" "4" "9" "3" "6" "1"
[81] "2" "2" "4" "9" "3" "1" "9" "8" "3" "7" "8" "8" "1" "5" "6" "9" "5" "8" "5" "8" "1" "2" "7" "5" "9" "4" "6" "7" "2" "9" "1" "7" "5" "5" "3" "1" "4" "6" "8" "2"
[121] "5" "1" "8" "7" "1" "4" "5" "2" "8" "5" "6" "9" "2" "3" "1" "4" "0" "4" "3" "5" "9" "8" "4" "5" "7" "7" "5" "7" "4" "6" "9" "8" "5" "7" "4" "8" "0" "3" "9" "3"
[161] "4" "5" "6" "7" "7" "7" "4" "8" "2" "4" "2" "3" "0" "9" "8" "5" "4" "2" "1" "0" "7" "4" "6" "0" "5" "0" "6" "2" "3" "7" "1" "1" "4" "1" "8" "7" "7" "9" "5" "4"
[201] "1" "8" "2" "1" "5" "3" "0" "4" "6" "4" "7" "4" "9" "8" "3" "5" "8" "1" "9" "4" "1" "2" "6" "7" "3" "9" "8" "7" "6" "7" "5" "5" "9" "1" "6" "5" "5" "4" "3" "9"
[241] "4" "6" "0" "7" "7" "0" "6" "2" "9" "1" "4" "5" "7" "1" "1" "9" "6" "4" "7" "7" "6" "8" "6" "5" "4" "2" "1" "6" "7" "6" "6" "0" "4" "2" "9" "8" "3" "1" "6" "5"
[281] "2" "6" "2" "4" "3" "8" "6" "8" "3" "7" "2" "0" "5" "6" "6" "8" "0" "6" "9" "3" "7" "6"
sum(as.integer(b))
[1] 1366这适用于我的设置(即Mac与R2.14.2，32位)，没有任何额外的软件包.在32位和64位的普通会话中也尝试过，他们都给了1366。
https://stackoverflow.com/questions/22318985
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