#2281: properFraction implemented with modf primitive?
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Reporter: guest | Owner:
Type: proposal | Status: new
Priority: normal | Component: Compiler
Version: 6.8.2 | Severity: normal
Keywords: | Testcase:
Architecture: Multiple | Os: Multiple
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I need a fast 'fraction' function for Double.
I can use 'properFraction', but its Double instance uses 'decodeFloat',
which is rather slow.
It's also clumsy to use, because I have to provide an Integral type,
although I'm not interested in the integral part.
I can use (x - int2Double (double2Int x)) but this fails for x beyond the
Int number range, and it is hard to fix that for an unknown implementation
of Double.
What about a 'modf' primitive which either calls 'modf' from standard C
library
or invokes an appropriate FPU command?
If Double is in IEEE format the 'fraction' command could also be
implemented quite efficiently by some bit masking without the FPU.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2281>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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