如何从Double而不是Haskell中的科学计数法获取十进制字符串? [英] How to get a decimal string from a Double instead of scientific notation in Haskell?

问题描述

我需要将数字列表除以100以进行打印，例如:

I need to divide a list of numbers by 100 to be printed, for example:

map (/100) [29, 3, 12]

产生:

[0.29,3.0e-2,0.12]

但是我需要:

[0.29,0.03,0.12]

我如何在Haskell中执行此操作?任何想法真的很感激.

How do I do this in Haskell? Any ideas really appreciated.

推荐答案

0.03和3.0e-2是相同的数字.在内部，GHC使用 showFloat 进行打印，只要绝对值在0.1到9,999,999范围之外，就会产生科学计数法.

0.03 and 3.0e-2 are the same number. Internally, GHC uses showFloat to print it, which will result in the scientific notation whenever the absolute value is outside the range 0.1 and 9,999,999.

因此，您必须自己打印值，例如使用printf : showFFloat"rel =" noreferrer> showFFloat 来自Numeric:

Therfore, you have to print the values yourself, for example with printf from Text.Printf or showFFloat from Numeric:

import Numeric

showFullPrecision :: Double -> String
showFullPrecision x = showFFloat Nothing x ""

main = putStrLn (showFullPrecision 0.03)

根据所需的输出，您需要编写更多功能.

Depending on your desired output, you need to write some more functions.

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