cosine.hh

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                             */
/*   This file is part of the C++-library RFFGen.                              */
/*   Copyright 2015 Lars Lubkoll                                               */
/*                                                                             */
/*   RFFGen is free software: you can redistribute it and/or modify            */
/*   it under the terms of the GNU General Public License as published by      */
/*   the Free Software Foundation, either version 3 of the License, or         */
/*   (at your option) any later version.                                       */
/*                                                                             */
/*   RFFGen is distributed in the hope that it will be useful,                 */
/*   but WITHOUT ANY WARRANTY; without even the implied warranty of            */
/*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             */
/*   GNU General Public License for more details.                              */
/*                                                                             */
/*   You should have received a copy of the GNU General Public License         */
/*   along with RFFGen.  If not, see <http://www.gnu.org/licenses/>.           */
/*                                                                             */
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#ifndef RFFGEN_CMATH_COSINE_HH
#define RFFGEN_CMATH_COSINE_HH

#include <cmath>
#include "../Util/base.hh"
#include "../Util/chainer.hh"

namespace RFFGen
{
  namespace CMath
  {
    struct Cos : Base , Chainer<Cos>
    {
      using Chainer<Cos>::operator ();
      explicit Cos(double x=0.)
      {
        update(x);
      }

      void update(const double& x)
      {
        sinx = ::sin(x);
        cosx = ::cos(x);
      }

      double d0() const noexcept { return cosx; }

      template < int = -1 >
      double d1(double dx=1.) const { return -sinx*dx; }

      template < int = -1 , int = -1 >
      double d2(double dx=1., double dy=1.) const { return -cosx*dx*dy; }

      template < int = -1, int = -1 , int = -1 >
      double d3(double dx=1., double dy=1., double dz=1.) const { return sinx*dx*dy*dz; }

    private:
      double sinx, cosx;
    };

    template < class Function ,
               class = std::enable_if_t< std::is_base_of<Base,Function>::value > >
    auto cos(const Function& f)
    {
      return Cos()(f);
    }
  }
}

#endif // RFFGEN_CMATH_COSINE_HH