[trailer]

Dear Foamers,


I am trying to create a preconditioner for a block Coupled solver in foam-extend based on BlockBiCGStabSolver.


However, I am getting the following error:

error: passing ‘const Foam::BlockBiCGStabSolver<Foam::Vector<double> >’ as ‘this’ argument discards qualifiers [-fpermissive]

In my preconditioner class (.H), I have:

 autoPtr<BlockBiCGStabSolver<Type> > solverPtr_;

In the .C file this is initialized as:

    solverPtr_( 
                    new BlockBiCGStabSolver<Type>
                     (
                        "test",
                        matrix,
                        dict                     
                    )
               )

In the preconditioner class, the virtual precondition function is defined as:

template<class Type>
void Foam::BlockMyPrecon<Type>::precondition
(
    Field<Type>& x,
    const Field<Type>& b
)const
{
    solverPtr_->solve(x, b);
}

Why is this error appearing? Am I not creating the solverPtr_ correctly?


If I use a raw pointer or std::unique_ptr, I get no compilation errors and the solver works.


Note: I got it to also work with

const_cast< autoPtr<BlockBiCGStabSolver<Type> > & >( solverPtr_ )->solve(x ,b);

although I do not know if this is the best approach.

[dlahaye]

Not sure.

I imagine, however, that the code that already exists gives examples on how to accomplish this.

I am happy to look further into this.

Cheers, Domenico.

[trailer]

Originally Posted by dlahaye

Not sure.

I imagine, however, that the code that already exists gives examples on how to accomplish this.

I am happy to look further into this.

Cheers, Domenico.

I could not find any example of already existing implementation for creating a preconditioner from an already existing solver.

Upon closure inspection, the problem seem the be because of the virtual function for preconditioning:

        //- Execute preconditioning
        virtual void precondition
        (
            Field<Type>& x,
            const Field<Type>& b
        ) const;

This has a const at the end of the function parameters to not change anything inside the class.


However, the virtual solve function in the solvers is:

        virtual BlockSolverPerformance<Type> solve
        (
            Field<Type>& x,
            const Field<Type>& b
        );

Since the latter is missing the const keyword, the compiler gives an error upon compilation.



However, I do not understand why I was able to compile the code with a raw pointer/c++ smart pointer

[dlahaye]

For preconditioners

https://github.com/OpenFOAM/OpenFOAM...reconditioners