埃尔朗和大数字 [英] Erlang and Big Numbers

问题描述

我正在尝试将pi存储到大约200位小数，erlang的大小可以约为15位数字，如何保留原始内容并将其用于进一步的计算？

I am trying to store pi to about 200 decimal places, erlang concats it to about 15 digits, how can I keep the original and have it used in further calculations?

1> P = 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513
282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233
786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367
892590360011330530548820466521384146951941511609433057270365759591953092186117381932611793105118548074462379962749567351
885752724891227938183011949129833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467
669405132000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923542019956112
129021960864034418159813629774771309960518707211349999998372978049951059731732816096318595024459455346908302642522308253
344685035261931188171010003137838752886587533208381420617177669147303598253490428755468731159562863882353787593751957781
857780532171226806613001927876611195909216420198938095257201065485863278865936153381827968230301952035301852968995773622
599413891249721775283479131515574857242454150695950829533116861727855889075098381754637464939319255060400927701671139009
848824012858361603563707660104710181942955596198946767837449448255379774726847104047534646208046684259069491293313677028
989152104752162056966024058038150193511253382430035587640247496473263914199272604269922796782354781636009341721641219924
586315030286182974555706749838505494588586926995690927210797509302955321165344987202755960236480665499119881834797753566
369807426542527862551818417574672890977772793800081647060016145249192173217214772350141441973568548161361157352552133475
741849468438523323907394143334547762416862518983569485562099219222184272550254256887671790494601653466804988627232791786
0857843838279679766814541009538837863609506800642251252051173929848960841284886.
3.141592653589793
2> P.
3.141592653589793

推荐答案

虽然Erlang有arbirary大整数，浮点数表示为 IEEE 754 双打。在Erlang中没有任意精度的内置浮点类型。

While Erlang has arbirary big integers, floating point numbers are represented as IEEE 754 doubles. There is no built-in floating point type with arbitrary precision in Erlang.

如果您需要任意精度的浮动计算，通常需要使用数学或MAPLE等语言。

If you need floating calculations with arbitrary precision you usually have to resort to languages like Mathematica or MAPLE.

您可以很容易地在Erlang中构建自己的任意精度浮点，而不是通过将它们存储为两个整数的元组 - 一个用于小数，一个用于指数。然后，您必须编写自己的算术函数，不能使用正常的运算符。

You could build your own arbitrary precision floats in Erlang quite easily however by storing them as tuples of two integers – one for the fraction and one for the exponent. You then have to write your own arithmetic functions and can't use the normal operators.

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