Can't retrieve bicgstab.error() nor bicgstab.iters() from the iterative solvers:

[tario]

Hello,

I want to retrieve some information from the iterative solver cg and bicgstab to monitor overall convergence of the simulation, but they are "uninitialized" hence last error and #iters are not available.

test code:

    solverPerf.initialResidual() = 0.03; // works, test    
    solverPerf.finalResidual() = (ScalarType)bicgstab.error(); // wrong value, test
    solverPerf.nIterations() = (ScalarType)bicgstab.iters(); 

warning:
clPBiCGStab_solve.C:75:62: warning: ‘((void)& bicgstab +40)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
solverPerf.finalResidual() = (ScalarType)bicgstab.error();
^
clPBiCGStab_solve.C:76:60: warning: ‘((void)& bicgstab +32)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
solverPerf.nIterations() = (ScalarType)bicgstab.iters();

How can I initialize the functions?

T.

[Karl Rupp]

Hi Tario,
how do you initialize the bicgstab object? Do you pass it to the solve() call? I can't say what's going on based on your description.
Best regards,
Karli

[tario]

This is the bicgstab related section:

viennacl::linalg::bicgstab_tag bicgstab(tolerance_, maxIter_); // Set solver tolerance and maximum iterations

// BLOCK PRECONDITIONER SETUP --------------------------------------------------------------------

viennacl::linalg::block_ilu_precond< viennacl::compressed_matrix<ScalarType>,
viennacl::linalg::ilu0_tag> vcl_block_ilu0(vcl_matrix, viennacl::linalg::ilu0_tag());

// ---------------------------------------------------------------------------------------------------------------

//solverPerf.initialResidual() = (ScalarType)cg_tag.error();

// Solve the linear system
vcl_psi = solve(vcl_matrix,
vcl_source,
viennacl::linalg::bicgstab_tag(),
vcl_block_ilu0);

[Karl Rupp]

Hi,

please use

vcl_psi = solve(vcl_matrix,
vcl_source,
bicgstab,   // pass the previously created object here
vcl_block_ilu0); 

for the solver call.

Best regards,
Karli