Line data    Source code

       1             : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
       2             :    Copyright (c) 2016-2021 The VES code team
       3             :    (see the PEOPLE-VES file at the root of this folder for a list of names)
       4             : 
       5             :    See http://www.ves-code.org for more information.
       6             : 
       7             :    This file is part of VES code module.
       8             : 
       9             :    The VES code module is free software: you can redistribute it and/or modify
      10             :    it under the terms of the GNU Lesser General Public License as published by
      11             :    the Free Software Foundation, either version 3 of the License, or
      12             :    (at your option) any later version.
      13             : 
      14             :    The VES code module is distributed in the hope that it will be useful,
      15             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
      16             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      17             :    GNU Lesser General Public License for more details.
      18             : 
      19             :    You should have received a copy of the GNU Lesser General Public License
      20             :    along with the VES code module.  If not, see <http://www.gnu.org/licenses/>.
      21             : +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
      22             : #ifndef __PLUMED_ves_GridLinearInterpolation_h
      23             : #define __PLUMED_ves_GridLinearInterpolation_h
      24             : 
      25             : #include <vector>
      26             : 
      27             : 
      28             : namespace PLMD {
      29             : 
      30             : 
      31             : class GridBase;
      32             : 
      33             : 
      34             : namespace ves {
      35             : 
      36             : class GridLinearInterpolation {
      37             : private:
      38             :   static double getGridValueWithLinearInterpolation_1D(GridBase* grid_pntr, const std::vector<double>& arg);
      39             :   static double getGridValueWithLinearInterpolation_2D(GridBase* grid_pntr, const std::vector<double>& arg);
      40             :   static double getGridValueWithLinearInterpolation_ND(GridBase* grid_pntr, const std::vector<double>& arg);
      41             :   static double getGridValueAndDerivativesWithLinearInterpolation_1D(GridBase* grid_pntr, const std::vector<double>& arg, std::vector<double>& der);
      42             :   static double getGridValueAndDerivativesWithLinearInterpolation_ND(GridBase* grid_pntr, const std::vector<double>& arg, std::vector<double>& der);
      43             :   static double linearInterpolation(const double x, const double x0, const double x1, const double y0, const double y1);
      44             :   static double multiLinearInterpolation(const std::vector<double>& x, const std::vector<std::vector<double>>& points, std::vector<double>& values, const double dim);
      45             : public:
      46             :   static double getGridValueWithLinearInterpolation(GridBase* grid_pntr, const std::vector<double>& arg);
      47             :   static double getGridValueAndDerivativesWithLinearInterpolation(GridBase* grid_pntr, const std::vector<double>& arg, std::vector<double>& der);
      48             :   static std::vector<std::vector<unsigned>> getAdjacentIndices(GridBase* grid_pntr, const std::vector<double>& arg);
      49             :   static std::vector<std::vector<unsigned>> getAdjacentPoints(GridBase* grid_pntr, const std::vector<double>& arg);
      50             : };
      51             : 
      52             : 
      53             : inline
      54             : double GridLinearInterpolation::linearInterpolation(const double x, const double x0, const double x1, const double y0, const double y1) {
      55             :   // https://en.wikipedia.org/wiki/Linear_interpolation
      56     2624038 :   if(x1!=x0) {
      57     2586242 :     return y0 + (x-x0) * ((y1-y0)/(x1-x0));
      58             :   }
      59             :   else {
      60             :     return y0;
      61             :   }
      62             : }
      63             : 
      64             : 
      65             : inline
      66           0 : double GridLinearInterpolation::multiLinearInterpolation(const std::vector<double>& x, const std::vector<std::vector<double>>& points, std::vector<double>& values, const double dim) {
      67           0 :   for (unsigned direction = 0; direction < dim; ++direction) {
      68           0 :     unsigned shift = 1<<(direction+1); // shift by 2, then 4, then 8 etc
      69           0 :     for (unsigned i = 0; i < points.size(); i += shift) {
      70             :       // replace every second value with interpolated ones
      71           0 :       values[i] = linearInterpolation(
      72           0 :                     x[direction], points[i][direction], points[i+shift/2][direction], values[i], values[i+shift/2]);
      73             :     }
      74             :   }
      75           0 :   return values[0];
      76             : }
      77             : 
      78             : 
      79             : }
      80             : }
      81             : 
      82             : #endif