FYI I prefer fill over repeat in 99% of cases as it does not allocate. IIRC it doesn’t create an intermediate array, but may not be appropriate in this case.

I rely on experimentation. Just check the type of the output for various functions. Sometimes it matters how you call certain functions, for example map(x->2*x, v) returns an SVector if v is an SVector but map(i->2*v[i], 1:length(v)) will return a Vector (not a surprise if you think about it). If you are curious, you can also check what code is being called with @less, for example try @less [aux1d; aux1d].

It probably returns a matrix. To get a vector it should be repeat(aux1d, 2) instead.

@Domenico_Lahaye, here you don’t want an Array at all, but in general you should be aware that Julia (unlike e.g. Matlab) distinguishes vectors from Nx1 matrices. Therefore, you use zeros(N), ones(N), rand(N) and repeat(x, N) instead of zeros(N, 1), ones(N,1), rand(N, 1) and repeat(x, N, 1), etc.

I would like to add local variables to my function. The first variant works fine. The second variant fails. I fail to understand this behavior.

function generateLocalMatrix(element::Element)
h = element.area
e1 = element.e1
e2 = element.e2
Iloc = SVector(e1, e1, e2, e2)
Jloc = SVector(e1, e2, e1, e2)
# Kloc: local variable to be used in the future: goes fine - *no* memory allocations
Kloc = SVector(1., 2., 3., 4.)
Aloc = SVector(1/h, -1/h, -1/h, 1/h)
return Iloc, Jloc, Aloc
end

function generateLocalMatrix(element::Element)
h = element.area
e1 = element.e1
e2 = element.e2
Iloc = SVector(e1, e1, e2, e2)
Jloc = SVector(e1, e2, e1, e2)
# Kloc: local variable to be used in the future: goes fine - *no* memory allocations
Kloc = SVector(1., 2., 3., 4.)
# Lloc: another local variable to be used in the future: fials - causes memory allocations
Lloc = SMatrix{2,2}([1. 2.;3. 4.])
Aloc = SVector(1/h, -1/h, -1/h, 1/h)
return Iloc, Jloc, Aloc
end

@less shows the source file where the function is defined, at the function definition. It’s maybe more clear if you use it with a regular function. [aux1d; aux1d] is translated by Julia directly into vcat(aux1d, aux1d) so that’s why you see the definition of (one method for) vcat.