Can you try it not in global scope? On Thu, Feb 25, 2016 at 5:17 AM, abc <[email protected]> wrote:
> For the following matrix > my_matrix = randn(10000, 1000) > using eachindex to access all elements is much slower than using ranges > or even for el in my_matrix, even though it says in the documentation ( > http://docs.julialang.org/en/release-0.4/stdlib/arrays/#Base.eachindex) > that eachindex uses ranges for Arrays. > > Some code and numbers: > julia> sum = 0.0 > julia> @time for iter in eachindex(my_matrix) > sum += my_matrix[iter] > end > 1.288944 seconds (50.00 M allocations: 915.519 MB, 3.36% gc time) > julia> sum = 0.0 > julia> @time for i in 1:10000, j in 1:1000 > sum += my_matrix[i,j] > end > 0.681678 seconds (34.38 M allocations: 524.582 MB, 2.45% gc time) > julia> sum = 0.0 > julia> @time for el in my_matrix > sum += el > end > 1.063564 seconds (40.00 M allocations: 762.993 MB, 3.41% gc time) > > Am I reading the documentation wrong, or is there something strange with > the matrix indexing? Because as it is, I don't see any benefit of using > anything different than simple ranges for manipulating matrices. >
