diagonally_scaled_operator.hpp

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#pragma once
 
#include "fe/wedge/operators/shell/laplace_simple.hpp"
#include "linalg/operator.hpp"
#include "linalg/vector.hpp"
#include "linalg/vector_q1.hpp"
 
namespace terra::linalg {
 
/// @brief Given some operator \f$K\f$ and a vector \f$v\f$, this operator is equivalent to an operator \f$A\f$ defined as
///
/// \f[ A = \mathrm{diag}(v) K \f]
///
template < OperatorLike OperatorT >
class DiagonallyScaledOperator
{
  public:
    using OperatorType  = OperatorT;
    using SrcVectorType = SrcOf< OperatorT >;
    using DstVectorType = DstOf< OperatorT >;
    using ScalarType    = ScalarOf< DstVectorType >;
 
  private:
    OperatorT&     op_;
    SrcVectorType& diag_;
 
  public:
    explicit DiagonallyScaledOperator( OperatorT& op, SrcVectorType& diag )
    : op_( op )
    , diag_( diag ) {};
 
    void apply_impl( const SrcVectorType& src, DstVectorType& dst )
    {
        apply( op_, src, dst );
        scale_in_place( dst, diag_ );
    }
};
 
static_assert(
    linalg::OperatorLike< DiagonallyScaledOperator< fe::wedge::operators::shell::LaplaceSimple< double > > > );
 
} // namespace terra::linalg