Hi, the oddest thing about Julia is how it behaves in loops (especially For loops). The following example gives me an error, DataVar: Not Defined, and I cannot imagine why: function TestLogic(Nloops) for i in 1:Nloops println("i, Nloops = ",i,", ",Nloops) if (i == 1) …

[image] CosmoProf: I am aware of the “controversy” about For loops not knowing about variables defined outside of the loop. But here, DataVar is being defined INSIDE the loop! What’s going on?? The variable scope is each iteration of the for loop, not all iterations of the loop together. If …

Exactly. Put simply, no edit to the manual will help if people don’t know how to look up sections, just like with real books. You can put flashing neon lights on the section and it wouldn’t help if the reader hasn’t reached the page. That’s not to say this can’t be improved ever. I just remembered t…

[image] Tamas_Papp: I think the fundamental problem is people not reading the manual (multiple times, coming back to parts, as they would read a textbook on some nontrivial subject). I think a big issue is that the manual is not at all easy to search. Something simple that might help is to ma…

[image] lmiq: Yes, that is clear. Does that mean that gfortran is just too bad? EDIT: I get the exact same performance between them (and -march=native doesn’t seem to matter). Compiling with gfortran -O3 -march=native rootloop.f90 -shared -fPIC -o libloop.so gfortran -Ofast -march=native ro…

[image] Elrod: No. Adding -march=native gives me the same performance in Julia and gfortran. Thanks for the tip, yet now I am trying to reproduce exactly what I did before and I do not see that difference in performance anymore… :neutral_face: … Now I see that -O3 is enough to pair up perform…

Ha, I admit I didn’t try without -march=native to confirm. I just did and got the exact same performance as with it when using -O3. When using -Ofast, it was faster without -march=native. lol The problem is that sqrt limits the performance of this function, and that SIMD square roots with 4 or 8 el…

[image] StefanKarpinski: Scope behavior decisions are made entirely for the sake of user-facing semantics, not at all for the sake of the compiler. If we wanted something that was easy on the compiler, we wouldn’t have closures at all or would have closures that capture by value. Interesting!…

[image] Why not an even-harder scope? Internals & Design Having a lot of time thinking about it, I really believe that our current design is very close to optimal given just these assumptions: Locals may be implicitly declared by assignment The rules for all local scopes…

I don’t know why but a lot of people including me were asking about scope rules in the last few days, maybe astrology is real.

Thanks lungben, the local DataVar statement seems to have gotten this kind of loop to work as I expected it to work in the first place. While the discussion that my question triggered is all very interesting, and people seem to be repeating positions from previous debates, as a relative newbie to …

Julia's loop scope behavior differs from Fortran?

General Usage

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Julia's loop scope behavior differs from Fortran?

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