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A tiny error in linear PCG solver

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Old   October 7, 2017, 11:22
Default A tiny error in linear PCG solver
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A tiny error in linear PCG solver.
https://cpp.openfoam.org/v5/PCG_8C_source.html#l00066
It does one more iteration than specified in variable maxIter_ (which is read from system/fvSolution dictionary):
Code:
// “PCG.C”
Foam::solverPerformance Foam::PCG::solve
(
    ...
) const
{
    ...
    // --- Solver iteration
    do
    {
        ...
    } while
    (
        (
            solverPerf.nIterations()++ < maxIter_
            ...
        )
        ...
    );
    ...
}
Here the loop condition is evaluated first, then number of iterations is incremented. The sequence of operations must be in the reverse order:
Code:
// “PCG.C”
Foam::solverPerformance Foam::PCG::solve
(
    ...
) const
{
    ...
    // --- Solver iteration
    do
    {
        ...
    } while
    (
        (
            ++solverPerf.nIterations() < maxIter_
            ...
        )
        ...
    );
    ...
}
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Old   October 9, 2017, 04:37
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Tobias Holzmann
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Hi Sergei,

I came across of that problems several times but never thought about that However, based on your post, I thought it is worth to mention in the bug-tracking system:

https://bugs.openfoam.org/view.php?id=2716
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Last edited by Tobi; October 14, 2017 at 06:54.
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Old   October 9, 2017, 07:26
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It is already resolved by the commit: https://github.com/OpenFOAM/OpenFOAM...7f0fa442d4ac56

In addition henry changed it in two other gradient based solvers
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Old   October 14, 2017, 06:32
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Hi, Tobias. Thanks for taking a burden of posting a bug report from me. The error was found a while ago but was left where it sat till recent moment. Sometimes searching for a bug in the code can be fun.
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