[yfjok22]

Hello, friends, I'm now dealing with linear iterative solvers in Openfoam. After several days' code reading, I have got a small problem in ldumatrix solver.
I'm now reading the code of Preconditional CG method(PCG.C in Openfoam), and nearly have got through most of it. But there still exists a small problem in this part

// --- Calculate normalisation factor
scalar normFactor = this->normFactor(psi, source, wA, pA);

if (lduMatrix::debug >= 2)
{
Info<< " Normalisation factor = " << normFactor << endl;
}

// --- Calculate normalised residual norm
solverPerf.initialResidual() = gSumMag(rA)/normFactor;
solverPerf.finalResidual() = solverPerf.initialResidual();

I'm really curious with the normFactor part, which is defined in lduMatrixSolver.C

Foam::scalar Foam::lduMatrix::solver::normFactor
(
const scalarField& psi,
const scalarField& source,
const scalarField& Apsi,
scalarField& tmpField
) const
{
// --- Calculate A dot reference value of psi
matrix_.sumA(tmpField, interfaceBouCoeffs_, interfaces_);
tmpField *= gAverage(psi);

return
gSum(mag(Apsi - tmpField) + mag(source - tmpField))
+ solverPerformance::small_;

In this function, it seems to return |Ax-p|+|b-p|+Ɛ, which I can't find any relation with the definition of normalisation. In the comment, it says that the code wants to build up the normalised residual norm, but it should be rA/|rA|, so what does it mean in this part of code. Please help me figure out this problem.

Thank you for your time and regard
Frank Yu

[yfjok22]

Could anybody help me with this problem