helmholtz.h

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#pragma once
 
#include <cassert>
 
#include "blas.h"
#include "elliptic.h"
 
namespace dg{
 
template<class Matrix, class Container>
struct GeneralHelmholtz
{
    using matrix_type = Matrix;
    using container_type = Container;
    using value_type = get_value_type<Container>;
 
    GeneralHelmholtz() = default;
 
    GeneralHelmholtz( value_type alpha, Matrix matrix):
        m_alpha(alpha), m_matrix(matrix), m_chi( m_matrix.weights())
    {
        dg::blas1::copy( 1., m_chi);
    }
 
    template<class ...Params>
    void construct( Params&& ...ps)
    {
        //construct and swap
        *this = GeneralHelmholtz( std::forward<Params>( ps)...);
    }
 
    const Container& weights()const {return m_matrix.weights();}
    const Container& precond()const {return m_matrix.precond();}
 
    template<class ContainerType0, class ContainerType1>
    void symv( const ContainerType0& x, ContainerType1& y)
    {
        if( m_alpha != 0)
            blas2::symv( m_matrix, x, y);
        dg::blas1::pointwiseDot( 1., m_chi, x, -m_alpha, y);
 
    }
 
    Matrix& matrix(){
        return m_matrix;
    }
    const Matrix& matrix()const{
        return m_matrix;
    }
    value_type& alpha( ){  return m_alpha;}
    value_type alpha( ) const  {return m_alpha;}
    template<class ContainerType0>
    void set_chi( const ContainerType0& chi) {
        dg::blas1::copy( chi, m_chi);
    }
    const Container& chi() const{return m_chi;}
    private:
    value_type m_alpha;
    Matrix m_matrix;
    Container m_chi;
};
 
template<class Geometry, class Matrix, class Container>
using Helmholtz = GeneralHelmholtz<dg::Elliptic2d<Geometry,Matrix,Container>, Container>;
template<class Geometry, class Matrix, class Container>
using Helmholtz1d = GeneralHelmholtz<dg::Elliptic1d<Geometry,Matrix,Container>, Container>;
template<class Geometry, class Matrix, class Container>
using Helmholtz2d = GeneralHelmholtz<dg::Elliptic2d<Geometry,Matrix,Container>, Container>;
template<class Geometry, class Matrix, class Container>
using Helmholtz3d = GeneralHelmholtz<dg::Elliptic3d<Geometry,Matrix,Container>, Container>;
 
template< class Geometry, class Matrix, class Container>
struct Helmholtz2
{
    using container_type = Container;
    using geometry_type = Geometry;
    using matrix_type = Matrix;
    using value_type = get_value_type<Container>;
    Helmholtz2() {}
    Helmholtz2( const Geometry& g, value_type alpha = 1., direction dir = dg::forward, value_type jfactor=1.)
    {
        construct( g, alpha, dir, jfactor);
    }
    Helmholtz2( const Geometry& g, bc bcx, bc bcy, value_type alpha = 1., direction dir = dg::forward, value_type jfactor=1.)
    {
              construct( g, bcx, bcy, alpha, dir, jfactor);
    }
    void construct( const Geometry& g, bc bcx, bc bcy, value_type alpha = 1, direction dir = dg::forward, value_type jfactor = 1.)
    {
        m_laplaceM.construct( g, bcx, bcy, dir, jfactor);
        dg::assign( dg::evaluate( dg::one, g), temp1_);
        dg::assign( dg::evaluate( dg::one, g), temp2_);
        alpha_ = alpha;
    }
    void construct( const Geometry& g, value_type alpha = 1, direction dir = dg::forward, value_type jfactor = 1.)
    {
        construct( g, g.bcx(), g.bcy(), alpha, dir, jfactor);
    }
    void symv(const Container& x, Container& y)
    {
        if( alpha_ != 0)
        {
            blas2::symv( m_laplaceM, x, temp1_); // temp1_ = -nabla_perp^2 x
            blas1::pointwiseDivide(temp1_, chi_, y); //temp2_ = (chi^-1)*nabla_perp^2 x
            blas2::symv( m_laplaceM, y, temp2_);//temp2_ = nabla_perp^2 *(chi^-1)*nabla_perp^2 x
        }
        blas1::pointwiseDot( chi_, x, y); //y = chi*x
        blas1::axpby( 1., y, -2.*alpha_, temp1_, y);
        blas1::axpby( alpha_*alpha_, temp2_, 1., y, y);
    }
    const Container& weights()const {return m_laplaceM.weights();}
    const Container& precond()const {return m_laplaceM.precond();}
    value_type& alpha( ){  return alpha_;}
    value_type alpha( ) const  {return alpha_;}
    void set_chi( const Container& chi) {chi_=chi; }
    const Container& chi()const {return chi_;}
  private:
    Elliptic2d<Geometry, Matrix, Container> m_laplaceM;
    Container temp1_, temp2_;
    Container chi_;
    value_type alpha_;
};
template< class M, class V>
struct TensorTraits< GeneralHelmholtz<M, V> >
{
    using value_type  = get_value_type<V>;
    using tensor_category = SelfMadeMatrixTag;
};
template< class G, class M, class V>
struct TensorTraits< Helmholtz2<G, M, V> >
{
    using value_type  = get_value_type<V>;
    using tensor_category = SelfMadeMatrixTag;
};
 
 
} //namespace dg