On Wed, 2009-01-28 at 16:42 -0800, drblanco wrote:
I do already have the number I wanted, but was wondering how this could be made faster, or even why it's so slow. This is all on GHC 6.8.3 under OS X Intel, using ghc -O2.
I'm not exactly sure what's different, but for me it works pretty well. I put back in the Int64 type signature.
For comparison, the C code below runs in <1 second.
You've got a faster machine than me :-) I compiled both the Haskell and C versions to standalone executables with ghc/gcc -O2 and ran them with time. C version: $ time ./circ 3141592649589764829 real 0m2.430s user 0m2.428s sys 0m0.000s Haskell version: time ./circ2 3141592653589764829 real 0m2.753s user 0m2.756s sys 0m0.000s Not too bad I'd say! :-) I was using ghc-6.10 for this test. It would appear that ghc-6.8 is a bit slower, I get: 3141592653589764829 real 0m5.767s user 0m5.768s sys 0m0.000s Now the other difference is that I'm using a 64bit machine so perhaps ghc just produces terrible code for Int64 on 32bit machines. Duncan