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haskelltaylor-series

Taylor sequence for the exponential function in Haskell

I tried to implement the Taylor sequence for the exponential function and I get a huge load of errors, which I don't fully understand, as all the code segments in themselves work... Could someone explain the error and a workaround please: 

top x = map (x^) [0..]
bottom = foldr (*) 1 [1..]
whole x = zipWith (/) (top x) bottom

Thanks in advance!

Solution

  • Okay, I figured it out. The problem was that bottom wasn't actually a list of all possible factorials.

    To solve the problem, I had to use scanl instead of foldr:

    bottom = scanl (*) 1 [1..]