squared.hh

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                             */
/*   This file is part of the C++-library RFFGen.                              */
/*   Copyright 2015 Lars Lubkoll                                               */
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/*   RFFGen is free software: you can redistribute it and/or modify            */
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#ifndef RFFGEN_MATHEMATICAL_OPERATIONS_SQUARED_HH
#define RFFGEN_MATHEMATICAL_OPERATIONS_SQUARED_HH

#include <type_traits>
#include <utility>

#include "../Util/base.hh"
#include "../Util/computeSum.hh"
#include "../Util/computeProduct.hh"
#include "../Util/derivativeWrappers.hh"
#include "../Util/indexedType.hh"

namespace RFFGen
{
  template <class> struct Chainer;
  namespace MathematicalOperations
  {
    template <class> struct FunctionConceptCheck;
    template <class F, class = FunctionConceptCheck<F> >
    struct Squared : Base , Chainer< Squared< F , FunctionConceptCheck<F> > >
    {
      using Chainer< Squared< F , FunctionConceptCheck<F> > >::operator();
    private:
      template < class IndexedArgX , class IndexedArgY >
      using D2Sum = ComputeSum< ComputeProduct< D0<F> , D2<F,IndexedArgX,IndexedArgY> >,
      ComputeProduct< D1<F,IndexedArgY> , D1<F,IndexedArgX> > >;

      template < class IndexedArgX , class IndexedArgY , class IndexedArgZ >
      using D3Sum = ComputeSum< ComputeProduct< D0<F> , D3<F,IndexedArgX,IndexedArgY,IndexedArgZ> > ,
      ComputeProduct< D1<F,IndexedArgZ> , D2<F,IndexedArgX,IndexedArgY> > ,
      ComputeProduct< D1<F,IndexedArgY> , D2<F,IndexedArgX,IndexedArgZ> > ,
      ComputeProduct< D2<F,IndexedArgY,IndexedArgZ> , D1<F,IndexedArgX> > >;

    public:
      Squared() = default;

      template <class InitF>
      Squared(const InitF& f_)
        : f(f_)
      {
        updateResultOfD0();
      }

      template <class Arg>
      void update(Arg const& x)
      {
        f.update(x);
        updateResultOfD0();
      }

      template <int index, class Arg>
      void updateVariable(const Arg& x)
      {
        f.template updateVariable<index>(x);
      }

      const auto& d0() const noexcept
      {
        return resultOfD0;
      }

      template < int id , class Arg , class IndexedArg = IndexedType<Arg,id> , class = std::enable_if_t< ComputeProduct< D0<F> , D1<F,IndexedArg> >::present > >
      auto d1(Arg const& dx) const
      {
        return 2 * f.d0() * f.template d1<id>(dx);
      }

      template < int idx , int idy , class ArgX , class ArgY ,
                 class IndexedArgX = IndexedType<ArgX,idx> ,
                 class IndexedArgY = IndexedType<ArgY,idy> ,
                 class = std::enable_if_t< D2Sum<IndexedArgX,IndexedArgY>::present > >
      auto d2(ArgX const& dx, ArgY const& dy) const
      {
        return 2 * D2Sum<IndexedArgX,IndexedArgY>(  ComputeProduct< D0<F>             , D2<F,IndexedArgX,IndexedArgY> >( D0<F>(f)        , D2<F,IndexedArgX,IndexedArgY>(f,dx,dy) ),
                                                  ComputeProduct< D1<F,IndexedArgY> , D1<F,IndexedArgX> >( D1<F,IndexedArgY>(f,dy)     , D1<F,IndexedArgX>(f,dx) )
                                             )();
      }

        template < int idx , int idy , int idz , class ArgX , class ArgY , class ArgZ ,
                 class IndexedArgX = IndexedType<ArgX,idx> ,
                 class IndexedArgY = IndexedType<ArgY,idy> ,
                 class IndexedArgZ = IndexedType<ArgZ,idz> ,
                 class = std::enable_if_t< D3Sum<IndexedArgX,IndexedArgY,IndexedArgZ>::present > >
      auto d3(ArgX const& dx, ArgY const& dy, ArgZ const& dz) const
      {
        return 2 * D3Sum<IndexedArgX,IndexedArgY,IndexedArgZ>
              ( ComputeProduct< D0<F> , D3<F,IndexedArgX,IndexedArgY,IndexedArgZ> > ( D0<F>(f) , D3<F,IndexedArgX,IndexedArgY,IndexedArgZ>(f,dx,dy,dz) ),
                ComputeProduct< D1<F,IndexedArgZ> , D2<F,IndexedArgX,IndexedArgY> > ( D1<F,IndexedArgZ>(f,dz) , D2<F,IndexedArgX,IndexedArgY>(f,dx,dy) ),
                ComputeProduct< D1<F,IndexedArgY> , D2<F,IndexedArgX,IndexedArgZ> > ( D1<F,IndexedArgY>(f,dy) , D2<F,IndexedArgX,IndexedArgZ>(f,dx,dz) ),
                ComputeProduct< D2<F,IndexedArgY,IndexedArgZ> , D1<F,IndexedArgX> > ( D2<F,IndexedArgY,IndexedArgZ>(f,dy,dz) , D1<F,IndexedArgX>(f,dx) )
              )();
      }

    private:
      void updateResultOfD0()
      {
        resultOfD0 = f.d0() * f.d0();
      }

      F f;
      std::remove_const_t<std::remove_reference_t<decltype(std::declval<F>().d0())> > resultOfD0;
    };
  }
}

#endif // RFFGEN_MATHEMATICAL_OPERATIONS_SQUARED_HH