Am Freitag 30 April 2010 02:46:08 schrieb MAN:
I can't find the error in your code (assuming there is an error), so I'm checking the code you didn't write, and the only thing that set off an alarm was...
getFloat64le :: Get Double getFloat64le = getFloat (ByteCount 8) $ splitBytes . reverse
splitBytes :: [Word8] -> RawFloat
...that every chunk read in the Get monad is being reversed, so that you can take one float (and you are taking in over 26 million floats) in little endian. I really don't know if this hits performance, but I assume the C equivalent would be reading an array in reverse order. I am more than willing to believe this is not the cause of such performance loss, but can't find a reason.
The reversing doesn't matter much, using getFloat64be takes very nearly the same time.
PS1: "(e == True)" == "e"
Yes!
PS2: I know it's not important, but I can't help it: that is not an average you're computing...
Sort of a weighted average, where double #k is weighted 2^(k-1-n).