[julia-users] Re: Algebraic Multigrid

[Christoph Ortner]

It seems this was it. 

If I do the following:

function py_csc(A::SparseMatrixCSC)
    # create an empty sparse matrix in Python
    Apy = scipy_sparse.csc_matrix(size(A))
    # write the values
    Apy[:data] = copy(A.nzval)
    # write the indices
    Apy[:indices] = A.rowval - 1
    Apy[:indptr] = A.colptr - 1
    return Apy
end
py_csr(A::SparseMatrixCSC) = py_csc(A)[:tocsr]()


then replace 

# B_py_csr = scipy_sparse.csr_matrix(B)
B_py_csr = py_csr(B)

I now get reasonably timings.