[Haskell-cafe] rounding errors with real numbers.

[Chris Kuklewicz]

Your solution works, but is slightly wasteful with (repair) traversing
the whole list again.  Here is a slightly more efficient expression:

-- Precondition: The first parameter (xs) is sorted (ascending) :
--                 assert (all (zipWith (<=) (xs, tail xs)))
--               low' < high'
--               low  < high
normInterval :: [Double] -> Double -> Double -> [Double]
normInterval xs low high = let low' = head xs; high' = last xs;
                               scale = (high-low)/(high'-low')
                               middle = init (tail xs)
                           in (low : [scale*(x-low')+low) | x <-middle])++[high]


-- 
Chris