Fast multidimensional Arrays

[Steinhagelvoll via Digitalmars-d-learn]

On Monday, 29 August 2016 at 13:59:15 UTC, Daniel Kozak wrote:
> Dne 29.8.2016 v 11:53 Steinhagelvoll via Digitalmars-d-learn 
> napsal(a):
>
>> [...]
> It is unfair to compare different backend:
>
> gfortran -O3 -o test test.f90
> [kozak at dajinka ~]$ time ./test
>
> real    0m2.072s
> user    0m2.053s
> sys    0m0.013s
>
> gdc -O3 -o test test.d
> [kozak at dajinka ~]$ time ./test
>
> real    0m1.655s
> user    0m1.640s
> sys    0m0.010s
>
> Obviously ifort can use some special instruction on your CPU

This seems to be it. I also implemented it in C++ (because 
gfortran isn't the main focus of GNU) and this is the result:

$ ./cpp_test_clang
elapsed time 1.12785
$ ./cpp_test_gpp
elapsed time 1.24206
$ ./cpp_test_intel
elapsed time 0.298331

It is quite surprising that there is this much of a difference, 
even when all run sequential. I believe this might be specific to 
this small problem.