Line data    Source code

       1             : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
       2             :    Copyright (c) 2016-2018 The plumed team
       3             :    (see the PEOPLE file at the root of the distribution for a list of names)
       4             : 
       5             :    See http://www.plumed.org for more information.
       6             : 
       7             :    This file is part of plumed, version 2.
       8             : 
       9             :    plumed 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             :    plumed 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 plumed.  If not, see <http://www.gnu.org/licenses/>.
      21             : +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
      22             : #include "core/ActionRegister.h"
      23             : #include "tools/ConjugateGradient.h"
      24             : #include "ActionWithGrid.h"
      25             : #include "EvaluateGridFunction.h"
      26             : #include "Interpolator.h"
      27             : 
      28             : //+PLUMEDOC GRIDCALC FIND_GRID_MINIMUM
      29             : /*
      30             : Find the point with the lowest value of the function on the grid
      31             : 
      32             : \par Examples
      33             : 
      34             : */
      35             : //+ENDPLUMEDOC
      36             : 
      37             : //+PLUMEDOC GRIDCALC FIND_GRID_MAXIMUM
      38             : /*
      39             : Find the point with the highest value of the function on the grid
      40             : 
      41             : \par Examples
      42             : 
      43             : */
      44             : //+ENDPLUMEDOC
      45             : 
      46             : namespace PLMD {
      47             : namespace gridtools {
      48             : 
      49             : class FindGridOptimum : public ActionWithGrid {
      50             : private:
      51             :   bool domin;
      52             :   double cgtol;
      53             :   std::unique_ptr<Interpolator> function;
      54             : public:
      55             :   static void registerKeywords( Keywords& keys );
      56             :   explicit FindGridOptimum(const ActionOptions&ao);
      57           0 :   void setupOnFirstStep( const bool incalc ) override {
      58           0 :     plumed_error();
      59             :   }
      60             :   unsigned getNumberOfDerivatives() override ;
      61             :   void calculate() override ;
      62             :   std::vector<std::string> getGridCoordinateNames() const override ;
      63             :   const GridCoordinatesObject& getGridCoordinatesObject() const override ;
      64             :   double calculateValueAndDerivatives( const std::vector<double>& pp, std::vector<double>& der );
      65           0 :   void performTask( const unsigned& current, MultiValue& myvals ) const override {
      66           0 :     plumed_error();
      67             :   }
      68             : };
      69             : 
      70             : PLUMED_REGISTER_ACTION(FindGridOptimum,"FIND_GRID_MAXIMUM")
      71             : PLUMED_REGISTER_ACTION(FindGridOptimum,"FIND_GRID_MINIMUM")
      72             : 
      73           8 : void FindGridOptimum::registerKeywords( Keywords& keys ) {
      74           8 :   ActionWithGrid::registerKeywords( keys );
      75          16 :   keys.addInputKeyword("compulsory","ARG","grid","the label for the function on the grid that you would like to find the optimum in");
      76           8 :   keys.addFlag("NOINTERPOL",false,"do not interpolate the function when finding the optimum");
      77           8 :   keys.add("compulsory","CGTOL","1E-4","the tolerance for the conjugate gradient optimization");
      78          16 :   keys.addOutputComponent("optval","default","scalar","the value of the function at the optimum");
      79          16 :   keys.addOutputComponent("_opt","default","scalar","the values of the arguments of the function at the optimum can be referenced elsewhere in the input file "
      80             :                           "by using the names of the arguments followed by the string _opt");
      81           8 : }
      82             : 
      83           2 : FindGridOptimum::FindGridOptimum(const ActionOptions&ao):
      84             :   Action(ao),
      85             :   ActionWithGrid(ao),
      86           2 :   cgtol(0) {
      87           2 :   if( getName()=="FIND_GRID_MAXIMUM" ) {
      88           0 :     domin=false;
      89           2 :   } else if( getName()=="FIND_GRID_MINIMUM" ) {
      90           2 :     domin=true;
      91             :   } else {
      92           0 :     plumed_error();
      93             :   }
      94             :   // Create value for this function
      95           2 :   std::vector<std::string> argn( getGridCoordinateNames() );
      96           2 :   std::vector<unsigned> shape(0);
      97           5 :   for(unsigned i=0; i<argn.size(); ++i) {
      98           6 :     addComponent( argn[i] + "_opt", shape );
      99             :   }
     100           2 :   addComponent( "optval", shape );
     101           2 :   componentIsNotPeriodic( "optval" );
     102           2 :   bool nointerpol=false;
     103           2 :   parseFlag("NOINTERPOL",nointerpol);
     104           2 :   if( !nointerpol ) {
     105           2 :     parse("CGTOL",cgtol);
     106           4 :     function=Tools::make_unique<Interpolator>( getPntrToArgument(0), getGridCoordinatesObject() );
     107             :   }
     108           2 : }
     109             : 
     110           0 : unsigned FindGridOptimum::getNumberOfDerivatives() {
     111           0 :   return 0;
     112             : }
     113             : 
     114         240 : const GridCoordinatesObject& FindGridOptimum::getGridCoordinatesObject() const {
     115         240 :   ActionWithGrid* ag=ActionWithGrid::getInputActionWithGrid( getPntrToArgument(0)->getPntrToAction() );
     116         240 :   plumed_assert( ag );
     117         240 :   return ag->getGridCoordinatesObject();
     118             : }
     119             : 
     120           2 : std::vector<std::string> FindGridOptimum::getGridCoordinateNames() const {
     121           2 :   ActionWithGrid* ag=ActionWithGrid::getInputActionWithGrid( getPntrToArgument(0)->getPntrToAction() );
     122           2 :   plumed_assert( ag );
     123           2 :   return ag->getGridCoordinateNames();
     124             : }
     125             : 
     126         236 : double FindGridOptimum::calculateValueAndDerivatives( const std::vector<double>& pp, std::vector<double>& der ) {
     127         236 :   double val = function->splineInterpolation( pp, der );
     128             :   // We normalise the derivatives here and set them so that the linesearch is done over the cell that we know
     129             :   // in the grid that we know the minimum is inside
     130         236 :   std::vector<double> spacing( getGridCoordinatesObject().getGridSpacing() );
     131             :   double norm = 0;
     132         623 :   for(unsigned i=0; i<der.size(); ++i) {
     133         387 :     norm += der[i]*der[i];
     134             :   }
     135         236 :   norm = sqrt(norm);
     136         623 :   for(unsigned i=0; i<der.size(); ++i) {
     137         387 :     der[i] = spacing[i]*der[i] / norm;
     138             :   }
     139         236 :   if( domin ) {
     140             :     return val;
     141             :   }
     142             :   // If we are looking for a maximum
     143           0 :   for(unsigned i=0; i<der.size(); ++i) {
     144           0 :     der[i] = -der[i];
     145             :   }
     146           0 :   return -val;
     147             : }
     148             : 
     149           2 : void FindGridOptimum::calculate() {
     150           2 :   const GridCoordinatesObject& ingrid = getGridCoordinatesObject();
     151             :   Value* gval = getPntrToArgument(0);
     152           2 :   std::vector<double> optargs( gval->getRank() );
     153           2 :   std::vector<unsigned> gridind( gval->getRank() );
     154           2 :   double optval=gval->get( 0 );
     155           2 :   ingrid.getGridPointCoordinates( 0, gridind, optargs );
     156           2 :   unsigned nval = gval->getNumberOfValues();
     157             :   bool constant=true;
     158        2602 :   for(unsigned i=0; i<nval; ++i) {
     159        2600 :     double tval = gval->get( i );
     160        2600 :     if( domin && (tval<optval || std::isnan(optval)) ) {
     161             :       constant=false;
     162             :       optval=tval;
     163          33 :       ingrid.getGridPointCoordinates( i, gridind, optargs );
     164             :     }
     165        2600 :     if( !domin && (tval>optval || std::isnan(optval)) ) {
     166             :       constant=false;
     167             :       optval=tval;
     168           0 :       ingrid.getGridPointCoordinates( i, gridind, optargs );
     169             :     }
     170             :   }
     171             :   // This basically ensures we deal with cases where all points on the grid are infinity as isinf doesn't work on intel compiler
     172           2 :   if( constant ) {
     173           0 :     if( domin && gval->get(0)>=gval->get(1) ) {
     174           0 :       return;
     175           0 :     } else if( gval->get(0)<=gval->get(1) ) {
     176             :       return;
     177             :     }
     178             :   }
     179           2 :   if( std::isinf(optval) ) {
     180             :     return;
     181             :   }
     182             : 
     183           2 :   if( std::isnan(optval) ) {
     184           0 :     error("all values on grid are nans");
     185             :   }
     186             :   // And do conjugate gradient optimisation (because we can!!)
     187           2 :   if( cgtol>0 ) {
     188             :     ConjugateGradient<FindGridOptimum> myminimiser( this );
     189           2 :     myminimiser.minimise( cgtol, optargs, &FindGridOptimum::calculateValueAndDerivatives );
     190             :   }
     191             :   // And set the final value
     192           5 :   for(unsigned j=0; j<optargs.size(); ++j) {
     193           3 :     getPntrToComponent(j)->set( optargs[j] );
     194             :   }
     195           2 :   std::vector<double> optder( gval->getRank() );
     196           2 :   getPntrToComponent(optargs.size())->set( function->splineInterpolation( optargs, optder ) );
     197             : }
     198             : 
     199             : }
     200             : }