A CSR matrix consists of 3 arrays, how can I use it with the linear solvers e.g. CG?

[tario]

Hello,

ViennaCL works with matrices in CSR format which consists of:

1: A column index array int* p_c_idx = &(c_idx[0]) ;

2: A row index array int* p_r_idx = &(r_idx[0]) ;

3: A value array scalar* p_vals = &(vals[0]) ;

This (1,2,3) is what I have after importing and converting the matrix of my engineering application.

Then I have the vectors

const scalar B = source.cdata() ;
scalar X = psi.data() ;

How can I use the above to solve the system with the linear solvers cg and bicgstab?

T.

[tario]

I think, I made some progress here but there's one compile error left:

vclPCG.C:205:27: error: invalid use of non-static member function
ldu2vcl(matrix, vclMat);

The function is:

// Import the CSR matrix for use with ViennaCL
void ldu2vcl
(
    const Foam::lduMatrix & matrix, viennacl::compressed_matrix<scalar>& vclMat
)
{
    uint N_DIAG = matrix.diag().size();
    uint lduMatrixSIZE = matrix.lower().size() + matrix.upper().size() + matrix.diag().size(); // nnz

    // allocat mem for CSR sparse matrix 
    scalar * v = (scalar *)calloc(lduMatrixSIZE, sizeof(scalar));
    uint * c = (uint *)calloc(lduMatrixSIZE, sizeof(uint));
    uint * r = (uint *)calloc(N_DIAG + 2, sizeof(uint));

    ldu2csr(matrix,v,c,r);
    vclMat.set(r,c,v,N_DIAG,N_DIAG,lduMatrixSIZE);   // ViennaCL compressed_matrix structure

    // free and release the matrix mem
    free(v); free(r); free(c);  //colloc()  
}

And I use it here:

...
    viennacl::compressed_matrix<scalar> vclMat; // matrix
    ldu2vcl(matrix, vclMat); // this gives me the error
...

Do you have any hint what causes the problem?

T.

[Karl Rupp]

Hi tario,

I think the compilation problem requires more context to diagnose. It doesn't seem to be ViennaCL-related, but something related to the structure of your code.

Best regards,
Karli