OK, on Julia 0.3.0 on OSX, for N=1001 elapsed time: 0.722537543 seconds (960169036 bytes allocated, 11.71% gc time) elapsed time: 0.703546159 seconds (955424928 bytes allocated, 26.01% gc time) elapsed time: 0.692751989 seconds (955424928 bytes allocated, 23.39% gc time) (first run includes JIT) So I'm not sure whats going on for you?
Anyway, I tried to improve the speed, again for N=1001 elapsed time: 0.256739122 seconds (321392500 bytes allocated, 23.75% gc time) elapsed time: 0.259208305 seconds (320464768 bytes allocated, 17.49% gc time) elapsed time: 0.212410743 seconds (320464768 bytes allocated, 32.42% gc time) By preallocating everything: https://gist.github.com/IainNZ/c7dd570ffedbf629a81d All the effort is in `sparse` (you can check with profiler) Thanks, Iain On Tuesday, October 7, 2014 11:01:05 AM UTC-4, Iain Dunning wrote: > > At a glance, why build list only to just add it to J? Why not add it > directly to J, and add i to I. > > If I have a chance I'll look further. > > Which Julia? > > On Monday, October 6, 2014 1:51:36 PM UTC-4, Andrei Berceanu wrote: >> >> I have written the following Julia code to build a sparse matrix of >> dimension N^2xN^2 >> >> https://gist.github.com/berceanu/fe7e26840637517383d8 >> >> The code works (probably in a very suboptimal way) for small enough >> matrices, but for example if I set N=1000, genspmat(1000) quickly eats up >> my RAM and crashes Julia. I doubt that this is related to the storage of >> the sparse matrix itself, and suspect it has to do with the garbage >> collection inside the main loop of genspmat, but I have no idea of fixing >> it. Any suggestions? >> >> Thanks! >> >
