I’ve ported a bit of code from R/Matlab/C++ to Julia a couple of times over the past few years and can get things to work, but I’m still not familiar with the best-practice, particularly around type declarations. My goal is improved efficiency – I already have working code in the 3 languages mention…

[image] baptiste: I’m inferring that Vector is an alias for 1D array, and probably Matrix an alias for 2D arrays. This leaves me with the AbstractArray concept – probably overly general for a regular kind of array? Array is the built-in multidimensional array type, and in particular it is a f…

I think you probably want something like: struct Material{T<:Real} wavelength::Vector{T} alpha::Vector{Complex{T}} medium::T end That way, you aren’t defining a single type, you are defining a family of types Material{T} for any real type that you might want, e.g. Material{Float64} for…

That’s very helpful, thanks! The different kinds of arrays are stlll a bit mysterious to me, between Vector, Matrix, Array, AbstractArray, RowVector(which I saw mentioned but doesn’t seem to exist). I’m inferring that Vector is an alias for 1D array, and probably Matrix an alias for 2D arrays. Thi…

[image] baptiste: And then to initialise or define types of their entries I’m not sure if I should go for Complex{Float64}, or Complex{AbstractFloat}, or Complex{Real}. Here, go with Complex{Float64}. But instead of initializing as Ajk = Array{Complex{Float64}}(undef,(3, 3)) it is much eas…

[image] baptiste: function propagator_freespace_labframe(R::Matrix{Float64}, kn::Float64, AlphaBlocks::Array{Complex{Float64}}) N = size(R,2) A = Matrix{Complex{Float64}}(I, 3*N, 3*N) I3 = Matrix{Complex{Float64}}(I, 3, 3) For function arguments, you almost always want to be more generic. In…

Thanks so much for all the helpful directions. The code is indeed a direct port from Matlab (and R, and C++ Armadillo, all 3 with the same basic syntax), and while I was pretty sure this wouldn’t produce good Julia code, it’s hard for a novice to know the “rights” and “wrongs” without some sort of …

[image] stevengj: On a separate note, note that you are allocating tons of copies of your arrays with slicing expressions like AlphaBlocks[:,:,jj] , and your vectorized expressions allocate zillions of temporary arrays. You need to be cautious about writing Matlab-style code in Julia, which does…

[image] baptiste: My biggest doubt about this approach though, is that ultimately A appears in a 3Nx3N linear system A x = b (coupled-dipole equations), and if A is a NxN matrix of SMatrices I don’t really see how it’s going to work (ultimately some Lapack routine will need the 3Nx3N matrix, won…

Some doubts about types

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Some doubts about types

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