Line data    Source code

       1             : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
       2             :    Copyright (c) 2012-2023 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 "Function.h"
      24             : 
      25             : namespace PLMD {
      26             : namespace function {
      27             : 
      28             : //+PLUMEDOC FUNCTION PIECEWISE
      29             : /*
      30             : Compute a piece wise straight line through its arguments that passes through a set of ordered control points.
      31             : 
      32             : For variables less than the first
      33             : (greater than the last) point, the value of the first (last) point is used.
      34             : 
      35             : \f[
      36             : \frac{y_{i+1}-y_i}{x_{i+1}-x_i}(s-x_i)+y_i ;  if x_i<s<x_{i+1}
      37             : \f]
      38             : \f[
      39             : y_N ; if x>x_{N-1}
      40             : \f]
      41             : \f[
      42             : y_1 ; if x<x_0
      43             : \f]
      44             : 
      45             : Control points are passed using the POINT0=... POINT1=... syntax as in the example below
      46             : 
      47             : If one argument is supplied, it results in a scalar quantity.
      48             : If multiple arguments are supplied, it results
      49             : in a vector of values. Each value will be named as the name of the original
      50             : argument with suffix _pfunc.
      51             : 
      52             : \par Examples
      53             : 
      54             : \plumedfile
      55             : dist1: DISTANCE ATOMS=1,10
      56             : dist2: DISTANCE ATOMS=2,11
      57             : 
      58             : pw: PIECEWISE POINT0=1,10 POINT1=2,PI POINT2=3,10 ARG=dist1
      59             : ppww: PIECEWISE POINT0=1,10 POINT1=2,PI POINT2=3,10 ARG=dist1,dist2
      60             : PRINT ARG=pw,ppww.dist1_pfunc,ppww.dist2_pfunc
      61             : \endplumedfile
      62             : 
      63             : 
      64             : */
      65             : //+ENDPLUMEDOC
      66             : 
      67             : 
      68             : class Piecewise :
      69             :   public Function
      70             : {
      71             :   std::vector<std::pair<double,double> > points;
      72             : public:
      73             :   explicit Piecewise(const ActionOptions&);
      74             :   void calculate() override;
      75             :   static void registerKeywords(Keywords& keys);
      76             : };
      77             : 
      78             : 
      79       10424 : PLUMED_REGISTER_ACTION(Piecewise,"PIECEWISE")
      80             : 
      81           4 : void Piecewise::registerKeywords(Keywords& keys) {
      82           4 :   Function::registerKeywords(keys);
      83           4 :   keys.use("ARG");
      84           8 :   keys.add("numbered","POINT","This keyword is used to specify the various points in the function above.");
      85           8 :   keys.reset_style("POINT","compulsory");
      86           4 :   componentsAreNotOptional(keys);
      87           8 :   keys.addOutputComponent("_pfunc","default","one or multiple instances of this quantity can be referenced elsewhere "
      88             :                           "in the input file.  These quantities will be named with the arguments of the "
      89             :                           "function followed by the character string _pfunc.  These quantities tell the "
      90             :                           "user the values of the piece wise functions of each of the arguments.");
      91           4 : }
      92             : 
      93           3 : Piecewise::Piecewise(const ActionOptions&ao):
      94             :   Action(ao),
      95           3 :   Function(ao)
      96             : {
      97           9 :   for(int i=0;; i++) {
      98             :     std::vector<double> pp;
      99          24 :     if(!parseNumberedVector("POINT",i,pp) ) break;
     100           9 :     if(pp.size()!=2) error("points should be in x,y format");
     101           9 :     points.push_back(std::pair<double,double>(pp[0],pp[1]));
     102           9 :     if(i>0 && points[i].first<=points[i-1].first) error("points abscissas should be monotonously increasing");
     103           9 :   }
     104             : 
     105           6 :   for(unsigned i=0; i<getNumberOfArguments(); i++)
     106           4 :     if(getPntrToArgument(i)->isPeriodic())
     107           1 :       error("Cannot use PIECEWISE on periodic arguments");
     108             : 
     109           2 :   if(getNumberOfArguments()==1) {
     110           1 :     addValueWithDerivatives();
     111           1 :     setNotPeriodic();
     112             :   } else {
     113           3 :     for(unsigned i=0; i<getNumberOfArguments(); i++) {
     114           3 :       addComponentWithDerivatives( getPntrToArgument(i)->getName()+"_pfunc" );
     115           2 :       getPntrToComponent(i)->setNotPeriodic();
     116             :     }
     117             :   }
     118           2 :   checkRead();
     119             : 
     120           2 :   log.printf("  on points:");
     121           8 :   for(unsigned i=0; i<points.size(); i++) log.printf("   (%f,%f)",points[i].first,points[i].second);
     122           2 :   log.printf("\n");
     123           4 : }
     124             : 
     125          10 : void Piecewise::calculate() {
     126          25 :   for(unsigned i=0; i<getNumberOfArguments(); i++) {
     127             :     double val=getArgument(i);
     128             :     unsigned p=0;
     129          37 :     for(; p<points.size(); p++) {
     130          33 :       if(val<points[p].first) break;
     131             :     }
     132             :     double f,d;
     133          15 :     if(p==0) {
     134           5 :       f=points[0].second;
     135             :       d=0.0;
     136          10 :     } else if(p==points.size()) {
     137           4 :       f=points[points.size()-1].second;
     138             :       d=0.0;
     139             :     } else {
     140           6 :       double m=(points[p].second-points[p-1].second) / (points[p].first-points[p-1].first);
     141           6 :       f=m*(val-points[p-1].first)+points[p-1].second;
     142             :       d=m;
     143             :     }
     144          15 :     if(getNumberOfArguments()==1) {
     145           5 :       setValue(f);
     146           5 :       setDerivative(i,d);
     147             :     } else {
     148          10 :       Value* v=getPntrToComponent(i);
     149          10 :       v->set(f);
     150             :       v->addDerivative(i,d);
     151             :     }
     152             :   }
     153          10 : }
     154             : 
     155             : }
     156             : }
     157             : 
     158             :