Reported issue: https://github.com/JuliaLang/julia/issues/6681
kl. 13:56:29 UTC+2 mandag 28. april 2014 skrev Ivar Nesje følgende: > > It seems like Jeff was wrong in his statement in > 32384010f<https://github.com/JuliaLang/julia/commit/32384010fd689e0b6a77ee93b24613fb0bdb008f> > . > > This discussion belongs in an issue on github. Do you want to post it > there? > > You can also fix the problem a little prettier by adding a () around 3 of > the numbers. > > Ivar > > kl. 13:38:30 UTC+2 mandag 28. april 2014 skrev John Travers følgende: >> >> Hi all, >> >> I have found some odd performance scaling when summing and scaling more >> than three complex numbers, see the difference between sum5 and sum5b in >> this gist: https://gist.github.com/jtravs/11368929 >> >> Compare: >> >> julia> using testsums >> julia> dosums(Complex{Float64}) >> elapsed time: 0.022001424 seconds (28800096 bytes allocated) >> elapsed time: 0.00194736 seconds (96 bytes allocated) >> >> With: >> >> julia> dosums(Float64) >> elapsed time: 0.000664517 seconds (96 bytes allocated) >> elapsed time: 0.000782516 seconds (96 bytes allocated) >> >> It seems that splitting the sum into maximum of three operands greatly >> speeds up performance for Complex{Float64} whereas it has no significant >> effect for Float64. Does anyone know why? I often have to sum and scale 5 >> or more arrays in my codes and it would be unfortunate to have to hand >> block them into sets of three like in sum5b in the gist. >> >>
