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. > >
