deviator.hh

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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/*   This file is part of the C++-library RFFGen.                              */
/*   Copyright 2015 Lars Lubkoll                                               */
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#ifndef RFFGEN_LINEAR_ALGEBRA_DEVIATOR_HH
#define RFFGEN_LINEAR_ALGEBRA_DEVIATOR_HH

#include "../generate.hh"
#include "../identity.hh"
#include "trace.hh"
#include "unitMatrix.hh"

namespace RFFGen
{
  namespace Concepts { template <class> struct SymmetricMatrixConceptChecks; }
  namespace LinearAlgebra
  {
    template <class Matrix, class = Concepts::SymmetricMatrixConceptCheck<Matrix>>
    auto deviator(const Matrix& A)
    {
      return Identity<Matrix>(A) + (-1./dimension<Matrix>()) * ( trace(A) * Constant<Matrix>( unitMatrix<Matrix>() ) );
    }

    template <class Matrix>
    class Deviator : public decltype( deviator( std::declval<Matrix>() ) )
    {
    private:
      using Base = decltype( deviator( std::declval<Matrix>() ) );
    public:
      Deviator() = default;
      Deviator(const Matrix& A) : Base( deviator(A) )
      {}
    };
  }
}

#endif // RFFGEN_LINEAR_ALGEBRA_DEVIATOR_HH