Hash numbers in haskell

Question

How to get the number in decimal format when performing 1/200!

Prelude>factorial x = product([1..x])
Prelude>x = factorial 200
Prelude>1/x
0.0

Answer 1

You can use CReal :

Data.Number.CReal> showCReal 400 (1/product [1..200])
"0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000012679769534809624217530164"
Data.Number.CReal> showCReal 30 (1e375/product [1..200])
"1.267976953480962421753016371075"

400/ 30there are how many digits to display.

If you like speed Double, you might consider scaling each number before calculating the product.

>  product (map (100/) [1..200])
1.2679769534809638e25

This requires a bit of reinterpretation of the output.