28 lines
753 B
Haskell
28 lines
753 B
Haskell
import Control.Monad (forM_)
|
|
import Data.Number.CReal (CReal, showCReal)
|
|
import Text.Printf (printf)
|
|
|
|
ramfun :: CReal -> CReal
|
|
ramfun x = exp (pi * sqrt x)
|
|
|
|
-- Ramanujan's constant.
|
|
ramanujan :: CReal
|
|
ramanujan = ramfun 163
|
|
|
|
-- The last four Heegner numbers.
|
|
heegners :: [Int]
|
|
heegners = [19, 43, 67, 163]
|
|
|
|
-- The absolute distance to the nearest integer.
|
|
intDist :: CReal -> CReal
|
|
intDist x = abs (x - fromIntegral (round x))
|
|
|
|
main :: IO ()
|
|
main = do
|
|
let n = 35
|
|
printf "Ramanujan's constant: %s\n\n" (showCReal n ramanujan)
|
|
printf "%3s %34s%20s%s\n\n" " h " "e^(pi*sqrt(h))" "" " Dist. to integer"
|
|
forM_ heegners $ \h ->
|
|
let r = ramfun (fromIntegral h)
|
|
d = intDist r
|
|
in printf "%3d %54s %s\n" h (showCReal n r) (showCReal 15 d)
|