For storing explicit zeros you're best off modifying nzvals directly.
In what way are you specializing your banded getindex method? Is this a
classical banded but dense-within-the-band matrix, or general CSC sparse
but with additional knowledge that no nonzeros ever have i and j different
by more than the bandwidth? You're probably better off either making a new
type for this that just wraps a SparseMatrixCSC for storage and either
stores or is parameterized by the bandwidth, or using a different method
other than getindex for this. If you'll miss the syntax, you could write a
macro to locally replace getindex with your specialized version.
On Tuesday, August 11, 2015 at 1:00:58 PM UTC-7, Jared Crean wrote:
>
> For a problem I am working on, I need to be able to store explicit zeros
> in a SparseMatrixCSC. While the storage format supports this, the
> setindex! method does not. Also, for banded sparse matricies I can define a
> much more efficient getindex method than the generic one. When I define my
> own method (importing the one from Base and then creating a method with the
> same signature as the existing one) I get warnings of the type:
>
>
> Warning: Method definition
> getindex(Base.SparseMatrix.SparseMatrixCSC{#T<:Any, Ti<:Integer}, Integer,
> Integer) in module SparseMatrix at sparse/sparsematrix.jl:1232 overwritten
> in module PDESolverCommon at
> /users/creanj/.julia/v0.4/PDESolverCommon/src/sparse.jl:63.
>
> My question is in what contexts is the method overwritten? In my local
> context (the REPL session where I use the one I created). Do functions
> within Base use the one in Base or the local one?
>
> Jared Crean
>
>
>
