#2271: floor, ceiling, round :: Double -> Int are awesomely slow
------------------------------------------+---------------------------------
Reporter: dons | Owner: daniel.is.fischer
Type: bug | Status: patch
Priority: low | Milestone: 7.0.1
Component: libraries/base | Version: 7.1
Keywords: performance, math, double | Testcase:
Blockedby: | Difficulty: Unknown
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by daniel.is.fischer):
Ah, no. The `-0.0` doesn't come from the rounding, it's because of
{{{
case float2Int# x of
n -> (I# n, F# (x `minusFloat#` int2Float# n))
}}}
(analogous for Double) and (-0.0) - 0.0 gives (-0.0). The extra check for
zero will cost a bit of performance :(
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2271#comment:29>
GHC <http://www.haskell.org/ghc/>
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