My parameters are not updated when I re-solve it? about parametron.jl HOT 3 CLOSED

When you do

A = Parameter(model, val=A_val)

the model stores a reference to the Parameter A, and A in turn stores a reference to the Matrix A_val. If you subsequently do

A_val = randn(n, n)

you've now made it so that the variable A_val refers to different data than the reference that's stored in the Parameter A. Instead, you should be doing e.g.

A_val .= randn(n, n) # note the dot

or better yet:

randn!(A)

to modify the matrix A_val in place. The second A= Parameter(model, val=A_val) is then unnecessary.

See e.g. https://discourse.julialang.org/t/question-regarding-references/7610/7?u=tkoolen for more info on how references work in Julia.

from parametron.jl.

Feel free to ask more usage questions by the way, either here or (perhaps preferably) on discourse. Just closed the issue because there are no actionable items in the codebase.

from parametron.jl.

Thank you @tkoolen for your response.
I just noticed that in @expression and in @constraint sparse matrices are not accepted.
For example, A=spzeros(n,m). If I use
A_expr = @expression A or @constraint(model, A * X ==0)
It gives me this error:
ERROR: LoadError: MethodError: no method matching one(::Type{Any})
Closest candidates are:
one(::Type{Union{Missing, T}}) where T at missing.jl:87
one(::Missing) at missing.jl:83
one(::BitArray{2}) at bitarray.jl:400
...
Stacktrace:
[1] one(::Type{Any}) at ./missing.jl:87
[2] *(::SparseMatrixCSC{Float32,Int64}, ::Array{Variable,1})at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.1/SparseArrays/src/linalg.jl:53

from parametron.jl.