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Comment by jpfr | Hacker News Reader

Julia and Matlab use the same (Fortran-based) linear algebra codes in the background.

I think it is great to see that a port of the Fortran code in Julia is nearly as fast as the Fortran code itself. So you can take Julia and write concise Matlab-style code (vectorized everywhere) or write imperative code (loops everywhere) and be equally fast.

Note that the graphs in the post are biased. The Fortran version uses a different algorithm for the solver.

Edit: The Matlab code is highly obfuscated. That is not good for the sake of comparison.

https://github.com/precisesimulation/julia-matlab-fortran-fe...

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Except Julia vectorised is not as fast as Julia looped.

so this :

    for i = 1:size(a)[1]
        a[i] = 2a[i] + 3b[i]
    end

is faster than

    a = 2a .+ 3b

(although I haven't benchmarked it)

Here's someone that did : http://aflyax.github.io/de_vectorization-runtime/

but in 0.5 there are speedups, apparently.

Here's a stack overflow discussion on it

http://stackoverflow.com/questions/27928502/julia-vectorized...

Very interesting, just tested on 0.5 and vectorized can still be a magnitude slower.

ulia> @time vect(x, y, a, b) 0.000038 seconds (29 allocations: 37.406 KB) 1×2 Array{Float64,2}:

julia> @time devect(x, y, a, b) 0.000006 seconds (10 allocations: 512 bytes) 1×2 Array{Float64,2}:

julia> @time vect(x, y, a, b) 0.002324 seconds (73 allocations: 3.075 MB) 416×2 Array{Float64,2}:

julia> @time devect(x, y, a, b) 0.000206 seconds (18 allocations: 23.359 KB) 416×2 Array{Float64,2}:

Matlab uses mkl for linear algebra, not the old school Fortran reference routines.

Optionally. OpenBLAS and LAPACK are the default.

See here: https://github.com/JuliaLang/julia

  OpenBLAS — fast, open, and maintained basic linear algebra subprograms (BLAS) library, based on Kazushige Goto's famous GotoBLAS.

  LAPACK (>= 3.5) — library of linear algebra routines for solving systems of simultaneous linear equations, least-squares solutions of linear systems of equations, eigenvalue problems, and singular value problems.

  MKL (optional) – OpenBLAS and LAPACK may be replaced by Intel's MKL library

I have compiled Julia from source several times thx; my point was that MATLAB is not using reference Fortran routines.

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