Untiful sparse arrays in matrix equation solvers

[StefanMathis]

Hello :-)

Does anyone know a non-allocating way to create a unit-stripped view into a SparseMatrixCSC? Let's assume I have the following sparse array:

A = (sprand(3, 3, 0.5))u"1/s"

Now if I want to use ustrip directly on that matrix, it'll default to ustrip.(A), which will allocate memory (which we want to avoid). A workaround could be using a reinterpretation of A, as it is done in the ustrip() implementation for the Matrix type:

reinterpret(Unitful.numtype(eltype(A)), A)
ERROR: `reinterpret` on sparse arrays is discontinued.
Try reinterpreting the value itself instead.

:-(

Now let's assume we have the following idea:

nzval_ustripped = ustrip(A.nzval)
A_new = SparseMatrixCSC(A.m, A.n, A.colptr, A.rowval, nzval_ustripped)
ERROR: MethodError: no method matching SparseMatrixCSC(::Int64, ::Int64, ::Vector{Int64}, ::Vector{Int64}, ::Base.ReinterpretArray{Float64, 1, Quantity{Float64, 𝐓 ^-1, Unitful.FreeUnits{(s^-1,), 𝐓 ^-1, nothing}}, Vector{Quantity{Float64, 𝐓 ^-1, Unitful.FreeUnits{(s^-1,), 𝐓 ^-1, nothing}}}, false})

The problem here is that Base.ReinterpretArray is not a Vector, which is required by the SparseMatrixCSC type. And now I'm out of ideas ;-)

Does anyone else have an idea how we can have unit-stripped views into sparse matrices which can then be used for efficient linear algebra?

[briochemc]

FWIW, related:

• Unitful linear algebra #46
• Compatibility with backslash and sparse arrays #150
• https://github.com/goretkin/UnitfulLinearAlgebra.jl