Line data    Source code

       1             : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
       2             :    Copyright (c) 2012-2019 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             : #include <cmath>
      26             : 
      27             : using namespace std;
      28             : 
      29             : namespace PLMD {
      30             : namespace function {
      31             : 
      32             : //+PLUMEDOC FUNCTION PIECEWISE
      33             : /*
      34             : Compute a piece wise straight line through its arguments that passes through a set of ordered control points.
      35             : 
      36             : For variables less than the first
      37             : (greater than the last) point, the value of the first (last) point is used.
      38             : 
      39             : \f[
      40             : \frac{y_{i+1}-y_i}{x_{i+1}-x_i}(s-x_i)+y_i ;  if x_i<s<x_{i+1}
      41             : \f]
      42             : \f[
      43             : y_N ; if x>x_{N-1}
      44             : \f]
      45             : \f[
      46             : y_1 ; if x<x_0
      47             : \f]
      48             : 
      49             : Control points are passed using the POINT0=... POINT1=... syntax as in the example below
      50             : 
      51             : If one argument is supplied, it results in a scalar quantity.
      52             : If multiple arguments are supplied, it results
      53             : in a vector of values. Each value will be named as the name of the original
      54             : argument with suffix _pfunc.
      55             : 
      56             : \par Examples
      57             : 
      58             : \plumedfile
      59             : dist1: DISTANCE ATOMS=1,10
      60             : dist2: DISTANCE ATOMS=2,11
      61             : 
      62             : pw: PIECEWISE POINT0=1,10 POINT1=1,PI POINT2=3,10 ARG=dist1
      63             : ppww: PIECEWISE POINT0=1,10 POINT1=1,PI POINT2=3,10 ARG=dist1,dist2
      64             : PRINT ARG=pw,ppww.dist1_pfunc,ppww.dist2_pfunc
      65             : \endplumedfile
      66             : 
      67             : 
      68             : */
      69             : //+ENDPLUMEDOC
      70             : 
      71             : 
      72           6 : class Piecewise :
      73             :   public Function
      74             : {
      75             :   std::vector<std::pair<double,double> > points;
      76             : public:
      77             :   explicit Piecewise(const ActionOptions&);
      78             :   void calculate() override;
      79             :   static void registerKeywords(Keywords& keys);
      80             : };
      81             : 
      82             : 
      83        7837 : PLUMED_REGISTER_ACTION(Piecewise,"PIECEWISE")
      84             : 
      85           4 : void Piecewise::registerKeywords(Keywords& keys) {
      86           4 :   Function::registerKeywords(keys);
      87           8 :   keys.use("ARG");
      88          16 :   keys.add("numbered","POINT","This keyword is used to specify the various points in the function above.");
      89          12 :   keys.reset_style("POINT","compulsory");
      90           4 :   componentsAreNotOptional(keys);
      91             :   keys.addOutputComponent("_pfunc","default","one or multiple instances of this quantity can be referenced elsewhere "
      92             :                           "in the input file.  These quantities will be named with the arguments of the "
      93             :                           "function followed by the character string _pfunc.  These quantities tell the "
      94          16 :                           "user the values of the piece wise functions of each of the arguments.");
      95           4 : }
      96             : 
      97           3 : Piecewise::Piecewise(const ActionOptions&ao):
      98             :   Action(ao),
      99           4 :   Function(ao)
     100             : {
     101           9 :   for(int i=0;; i++) {
     102             :     std::vector<double> pp;
     103          24 :     if(!parseNumberedVector("POINT",i,pp) ) break;
     104           9 :     if(pp.size()!=2) error("points should be in x,y format");
     105          18 :     points.push_back(std::pair<double,double>(pp[0],pp[1]));
     106          21 :     if(i>0 && points[i].first<=points[i-1].first) error("points abscissas should be monotonously increasing");
     107           9 :   }
     108             : 
     109          12 :   for(unsigned i=0; i<getNumberOfArguments(); i++)
     110           4 :     if(getPntrToArgument(i)->isPeriodic())
     111           3 :       error("Cannot use PIECEWISE on periodic arguments");
     112             : 
     113           2 :   if(getNumberOfArguments()==1) {
     114           1 :     addValueWithDerivatives();
     115           1 :     setNotPeriodic();
     116             :   } else {
     117           5 :     for(unsigned i=0; i<getNumberOfArguments(); i++) {
     118           4 :       addComponentWithDerivatives( getPntrToArgument(i)->getName()+"_pfunc" );
     119           2 :       getPntrToComponent(i)->setNotPeriodic();
     120             :     }
     121             :   }
     122           2 :   checkRead();
     123             : 
     124           2 :   log.printf("  on points:");
     125          14 :   for(unsigned i=0; i<points.size(); i++) log.printf("   (%f,%f)",points[i].first,points[i].second);
     126           2 :   log.printf("\n");
     127           2 : }
     128             : 
     129          10 : void Piecewise::calculate() {
     130          25 :   for(unsigned i=0; i<getNumberOfArguments(); i++) {
     131             :     double val=getArgument(i);
     132             :     unsigned p=0;
     133          74 :     for(; p<points.size(); p++) {
     134          33 :       if(val<points[p].first) break;
     135             :     }
     136             :     double f,d;
     137          15 :     if(p==0) {
     138           5 :       f=points[0].second;
     139             :       d=0.0;
     140          10 :     } else if(p==points.size()) {
     141           8 :       f=points[points.size()-1].second;
     142             :       d=0.0;
     143             :     } else {
     144          12 :       double m=(points[p].second-points[p-1].second) / (points[p].first-points[p-1].first);
     145           6 :       f=m*(val-points[p-1].first)+points[p-1].second;
     146             :       d=m;
     147             :     }
     148          15 :     if(getNumberOfArguments()==1) {
     149           5 :       setValue(f);
     150             :       setDerivative(i,d);
     151             :     } else {
     152          10 :       Value* v=getPntrToComponent(i);
     153          10 :       v->set(f);
     154             :       v->addDerivative(i,d);
     155             :     }
     156             :   }
     157          10 : }
     158             : 
     159             : }
     160        5874 : }
     161             : 
     162             :