[julia-users] Re: Is Julia slow with large arrays?

[Lutfullah Tomak]

First thing I caught in your code

http://docs.julialang.org/en/release-0.4/manual/performance-tips/#avoid-changing-the-type-of-a-variable

make bar non-type-changing
function foo()
    array1 = rand(70, 1000)
    array2 = rand(70, 1000)
    array3 = rand(2, 70, 20, 20)
    bar = 0.0
    @time for l = 1:1000, k = 1:20, j = 1:20, i = 1:70
        bar = bar +
            (array1[i, l] - array3[1, i, j, k])^2 +
            (array2[i, l] - array3[2, i, j, k])^2
    end
end

Second, Julia checks array bounds so @inbounds macro before for-loop should 
help
improve performance. In some situation @simd may emit vector instructions 
thus faster
code.