Stefan, thanks.
On Friday, 18 March 2016 15:11:22 UTC+1, Stefan Karpinski wrote: > > This was one of the motivating issues for the function redesign which is > now on Julia master. If you try the latest development version of Julia, > these should both be much faster. > > On Fri, Mar 18, 2016 at 8:50 AM, Igor Cerovsky <igor.c...@2bridgz.com > <javascript:>> wrote: > >> Hello, >> >> By writing a code for unit normal scaling I've found a big differences >> related to where a function used in broadcast is defined, *globally* vs* >> locally*. Consider functions below: >> >> function scun2!(A) >> shift = mean( A, 1) >> stretch = std(A, 1) >> >> f(a, b, c) = (a - b) / c # defined locally >> broadcast!(f, A, A, shift, stretch) >> >> shift, stretch >> end >> >> f_scun(a, b, c) = (a - b) / c # defined globally >> function scun3!(A) >> shift = mean( A) >> stretch = std(A, 1) >> >> broadcast!(f_scun, A, A, shift, stretch) >> >> shift, stretch >> end >> >> Resulting performance is: >> >> R2 = copy(T) >> >> @time sh2, sc2 = scun2!(R2); >> >> 0.035527 seconds (19.51 k allocations: 967.273 KB) >> >> >> R3 = copy(T) >> >> @time sh3, sc3 = scun3!(R3); >> >> 0.009705 seconds (54 allocations: 17.547 KB) >> >> >> How can be explained, that if f_scun is defined outside the function the >> performance is 3.6 times better (number of allocations is also large)? I'm >> using Julia 0.4.3 >> >> Thank you, >> Igor >> >> >> >> >> >
