numericepsilon.hh

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#ifndef DUMUX_ASSEMBLY_NUMERIC_EPSILON_HH
#define DUMUX_ASSEMBLY_NUMERIC_EPSILON_HH
 
#include <dune/common/fvector.hh>
#include <dumux/common/parameters.hh>
#include <dumux/common/numericdifferentiation.hh>
 
namespace Dumux {

template<class Scalar, int numEq>
class NumericEpsilon
{
    using NumEqVector = Dune::FieldVector<Scalar, numEq>;
 
public:
    explicit NumericEpsilon(const std::string& paramGroup = "")
    {
        // get epsilons from input file with invalid default
        baseEps_ = getParamFromGroup<Scalar>(paramGroup, "Assembly.NumericDifference.BaseEpsilon", 1e-10);
        magnitude_ = getParamFromGroup<NumEqVector>(paramGroup, "Assembly.NumericDifference.PriVarMagnitude", NumEqVector(-1));
    }

    Scalar operator() (Scalar priVar, int priVarIdx) const noexcept
    {
        return magnitude_[priVarIdx] > 0.0 ? baseEps_*magnitude_[priVarIdx]
                                           : NumericDifferentiation::epsilon(priVar, baseEps_);
    }
 
private:
    Scalar baseEps_;
    NumEqVector magnitude_;
};
 
} // end namespace Dumux
 
#endif