On Wed, Nov 30, 2022 at 11:05:21PM -0500, David McBride wrote:
It is because (**) takes floating point numbers. In your first equation both 4s are different. The second 4 is an Integer but the first is a some Floating type aka 4.0.
Thank you David: I switched from x**1 to x^i and it worked fact :: Integer -> Integer fact n = product [1..n] expon :: Double -> Double expon x = sum [x^i/fromIntegral(fact(i)) | i <- [0..50]] $ ghci GHCi, version 9.2.4: https://www.haskell.org/ghc/ :? for help ghci> :l ePowerSeries.hs [1 of 1] Compiling Main ( ePowerSeries.hs, interpreted ) Ok, one module loaded. ghci> exp exp expon exponent ghci> expon 2 7.389056098930649 ghci> exp 2 7.38905609893065 I believe x^i has a similar effect to x**fromIntegral(i) -- Kind regards, Jonathan