On 17 Mar 2008, [EMAIL PROTECTED] wrote: > Hello David, > > Monday, March 17, 2008, 7:59:09 PM, you wrote: > >>> foreign import ccall unsafe "math.h log10" >>> c_log10 :: CDouble -> CDouble >>> >>> log10 :: Double -> Double >>> log10 x = realToFrac (c_log10 (realToFrac x)) > >> It's a bit sloppier, but shouldn't cause any trouble. And I've no >> idea how realToFrac is implemented, but would worry about it behaving >> oddly... for instance when given NaNs. > > it should be nop (no operation) in such cases
A related issue: http://hackage.haskell.org/trac/ghc/ticket/2110 Presumably everyone is aware of decodeFloat :: (RealFloat a) => a -> (Integer, Int) which really is a canonical representation of a floating point number. As for realToFrac, this really isn't okay: *GHCi> 0/0 NaN *GHCi> realToFrac (0/0) -Infinity Also, this one might surprise a few people. *GHCi> realToFrac (realToFrac 0.2 :: Ratio Int) -Infinity *GHCi> realToFrac 0.2 :: Ratio Int (-858993459)%0 Jed
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