Re: [Haskell-cafe] Unresolved overloading error

On 3/31/07, Scott Brown wrote:

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It's working now, thank you. I changed the definition to

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binom n j = div (fac n) ((fac j)*(fac (n - j)))

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bernoulli n p j = fromIntegral(binom n j)*(p ^ j) * ((1 - p)^(n - j))

As a matter of style suggestion, it might make 'binom' more clear if you use 'div' as an infix operator:

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binom n j = (fac n) `div` ( fac j * fac (n - j) ) And as a matter of efficiency, no one would write binom using factorial, but would rather write at least binom u k = (product [(u-i+1) | i <- [1..k]]) `div` (product [1..k]) and even better would be to do it this way -- bb u k = toInteger $ product [ (u-i+1) / i | i <- [1..k]] but that does not type (for a good reason). The issue is that it is

Bryan Burgers wrote: possible to prove that the above is an integer, but the compiler can't see that :-( That can be done as import Data.Ratio bb u k = numerator $ product [ (u-i+1) / i | i <- [1..k]] Of course, the above is fast if and only if the gcd operation in Data.Ratio has been well optimized. Jacques