Re: Why Octave is a bit slow

[Richard Crozier]

On 28/04/17 07:59, Mudit Sharma wrote:
> All,
>
> I was recently visiting this page about Julia ( language ) :
> https://julialang.org/
> and came to know that Octave is slower as compared to others ( please
> see the table given on the page ).
>  I would like to know why Octave becomes slower at times and what can be
> done to make it faster ?
>
> --
> Mudit


Probably because the benchmarks mostly use looped code which Octave is 
not optimised for. Octave would probably not perform so badly with code 
optimised for it, e.g. vectorised, for example it is much faster on the 
matrix multiplication. However, another reason for the difference is the 
lack of JIT functionality in Octave. If you have the capability or 
funding to bring this to Octave it would be a fantastic addition!

I had a look at their benchmark code, here:

https://github.com/JuliaLang/julia/blob/master/test/perf/micro/perf.m

as one example, pisum, has a vectorised version which they currently 
don't mention:

comparing in Octave, their own two benchmark codes on my machine:

>> function s = pisumvec(ignore)

    a = [1:10000];

    for j=1:500

        s = sum( 1./(a.^2));

    end

end

>> function sum = pisum(ignore)

    sum = 0.0;

    for j=1:500

        sum = 0.0;

        for k=1:10000

            sum = sum + 1.0/(k*k);

        end

    end

end

>> tic; pisum; toc;

Elapsed time is 10.2683 seconds.
>> tic; pisumvec; toc;

Elapsed time is 0.0357349 seconds.


Regards,

Richard

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