This is not really an answer to your question, but I think you could
write a slightly more efficient function to calculate the binomial
coefficient:
fac :: Integer -> Integer
fac n = product [1..n]
-- |Product of all positive integers less than or equal to n but
-- larger than s
facFrom :: Integer -> Integer -> Integer
facFrom s n | s > n = if s == 1 then 1 else 0
| otherwise = product [max (s + 1) 1 .. n]
boven :: Integer -> Integer -> Integer
boven n k = facFrom (n - k) n `div` fac k
This exploits the fact that "fac n" contains the computation for "fac (n - k)".
2009/2/5 Tsunkiet Man
Hello,
I'm new to Haskell and it seems like a very nice language to learn. However I'm not really familiar with the errormessages it produces. I am using a Helium interpreter. I've created the following module (however it is just a small sketch). I've written the following code:
fac :: Int -> Int fac n = product[1..n]
boven :: Int -> Int -> Int boven n k = (fac n) `div` fac k * fac (n-k)
bin :: Int -> Int -> Int -> Int bin n k p |(n-k)>0 && k>0 = (boven n k) * (p^k) * (1-p)^(n-k) |(n-k)<0 && k>0 = (boven n k) * (p^k) * (1/((1-p)^(-(n-k)))) |(n-k)<0 && k<0 = (boven n k) * (1/(p^(-k))) * (1/((1-p)^(-(n-k))))
When I load this into my interpreter it says:
Compiling ./Test.hs (11,55): Type error in infix application expression : 1 / ((1 - p) ^ (-(n - k))) operator : / type : Float -> Float -> Float does not match : Int -> Int -> Int (12,47): Type error in infix application expression : 1 / (p ^ (-k)) operator : / type : Float -> Float -> Float does not match : Int -> Int -> a (12,62): Type error in infix application expression : 1 / ((1 - p) ^ (-(n - k))) operator : / type : Float -> Float -> Float does not match : Int -> Int -> a Compilation failed with 3 errors
Some details that might be usefull:
Line 11 is |(n-k)<0 && k>0 = (boven n k) * (p^k) * (1/((1-p)^(-(n-k)))) Line 12 is |(n-k)<0 && k<0 = (boven n k) * (1/(p^(-k))) * (1/((1-p)^(-(n-k))))
So my question is: how can I fix these errors?
(I used these lines of codes because it is not possible to use a negative exponent in the Helium interpreter.)
Thank you for answering my question!
Greetings JTKM _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe