On Sunday 05 February 2012, 18:18:54, Thomas Engel wrote:
-- sums ys, where sums ks = zipWith (+) ks
Sigh, that's what you get for hopping to and fro while writing a mail. That should have been sums ks = zipWith (+) ks (tail ks) like for differences
-- or areas xs ys = zipWith (*) (differenses xs) (means ys) -- where means zs = map (/ 2) (sums zs)
I have changed the functions according your advice. But still I get an error:
differences :: Num a => [a] -> [a] differences xs = zipWith subtract xs (tail xs)
areas :: Floating a => [a] -> [a] -> [a] areas xs ys = zipWith (*) (differences xs) (means ys) where means zs = map (/ 2) (sums zs) where sums ks = zipWith (+) ks
It wasn't meant to be understood so, I intended differences etc. to be top- level functions, that's more readable.