unsafe_wrap from a pointer from a Julia array

[Sheehan Olver]

In some high performance code I want to convert an 2 x n `Matrix{Float64}` to a n long `Matrix{Vec{2,Float64}}`with no memory allocation (both types will store memory in the same order).  The following works:

v=rand(2,100)

w=unsafe_wrap(Vector{Vec{2,Float64}},

            reinterpret(Ptr{Vec{2,Float64}},pointer(v)),

            size(pts,1),true)

The variable v is a throw away variable, however, and as I understand it, the way its written the memory for w will be freed as soon as v is no longer referenced.  Is there any way to tell the garbage collector to not collect v?

[Gunnar Farnebäck]

Is this what you're looking for?

julia> using SIMD

julia> v = rand(2, 5)
2×5 Array{Float64,2}:
 0.391832  0.785861  0.352291  0.874891  0.874593
 0.697768  0.51637   0.711525  0.400077  0.266559

julia> w = reinterpret(Vec{2, Float64}, vec(v))
5-element Array{SIMD.Vec{2,Float64},1}:
 Float64⟨0.391832,0.697768⟩
 Float64⟨0.785861,0.51637⟩
 Float64⟨0.352291,0.711525⟩
 Float64⟨0.874891,0.400077⟩
 Float64⟨0.874593,0.266559⟩

[Sheehan Olver]

👍 

Sent from my iPhone

[Sheehan Olver]

Oh wait, I was referring to Vec from FixedSizeArrays.jl , not from SIMD

[Sheehan Olver]

Though that code works too for FixedSizeArrays