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I need to divide a list of numbers by 100 to be printed, for example:
map (/100) [29, 3, 12]
produces:
[0.29,3.0e-2,0.12]
however I need:
[0.29,0.03,0.12]
How do I do this in Haskell? Any ideas really appreciated.
272
Scipen: A penalty to be applied when deciding to print numeric values in fixed or exponential notation. Positive values bias towards fixed and negative towards scientific notation: fixed notation will be preferred unless it is more than scipen digits wider.
Scientific notation is a way of writing very large or very small numbers. A number is written in scientific notation when a number between 1 and 10 is multiplied by a power of 10. For example, 650,000,000 can be written in scientific notation as 6.5 ✕ 10^8.
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.
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)
Depending on your desired output, you need to write some more functions.
117
What works for me is: cabal install numbers and then in GHCi
λ: import Data.Number.CReal
λ: map (/(100 :: CReal)) [29,3,12]
[0.29,0.03,0.12]
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