[Haskell-beginners] numerical integration over lists

Thomas Engel thomas.engel1 at gmx.net
Sun Feb 5 17:32:44 CET 2012


Hello Benjamin,

> 
>    [Float] is a list of floats. (Float) is not.
thanks for pointing out an error. But now I get an other error message.

integriereListe::[Float]->[Float]->[Float]
integriereListe [][]  = 0.0
integriereListe (x:xs) (y:ys)   = (y - y2) / 2.0 * (x2 -x)
                                 where
                                 x2 = head xs
                                 y2 = head ys

No instance for (Fractional [Float])
      arising from a use of `/'
    Possible fix: add an instance declaration for (Fractional [Float])
    In the first argument of `(*)', namely `(y - y2) / 2.0'
    In the expression: (y - y2) / 2.0 * (x2 - x)
    In an equation for `integriereListe':
        integriereListe (x : xs) (y : ys)
          = (y - y2) / 2.0 * (x2 - x)
          where
              x2 = head xs
              y2 = head ys

Thomas



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