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             : 
      23             : #include "TargetDistribution.h"
      24             : 
      25             : #include "core/ActionRegister.h"
      26             : 
      27             : 
      28             : namespace PLMD {
      29             : namespace ves {
      30             : 
      31             : //+PLUMEDOC VES_TARGETDIST TD_EXPONENTIAL
      32             : /*
      33             : Exponential distribution (static).
      34             : 
      35             : Employ a target distribution given by an
      36             : [exponential distribution](https://en.wikipedia.org/wiki/Exponential_distribution)
      37             : that is defined as
      38             : 
      39             : $$
      40             : p(s) =
      41             : \lambda e^{-\lambda(s-a)}
      42             : $$
      43             : 
      44             : where $a$ is the minimum of the distribution that is defined on the interval $[a,\infty)$,
      45             : and $\lambda>0$ is the so-called rate parameter.
      46             : 
      47             : The minimum $a$ is given using the MINIMUM keyword, and the rate parameter $\lambda$ is given
      48             : using the LAMBDA keyword.
      49             : 
      50             : This target distribution action is only defined for one dimension, for multiple dimensions
      51             : it should be used in combination with [TD_PRODUCT_DISTRIBUTION](TD_PRODUCT_DISTRIBUTION.md) action.
      52             : 
      53             : ## Examples
      54             : 
      55             : Exponential distribution with $a=10.0$ and $\lambda=0.5$
      56             : 
      57             : ```plumed
      58             : td: TD_EXPONENTIAL  MINIMUM=-10.0  LAMBDA=0.5
      59             : ```
      60             : 
      61             : The exponential distribution is only defined for one dimension so for multiple
      62             : dimensions we have to use it in combination with the [TD_PRODUCT_DISTRIBUTION](TD_PRODUCT_DISTRIBUTION.md) action as shown in
      63             : the following example where we have a uniform distribution for argument 1 and
      64             : and an exponential distribution for argument 2
      65             : 
      66             : ```plumed
      67             : td_uni: TD_UNIFORM
      68             : 
      69             : td_exp: TD_EXPONENTIAL  MINIMUM=-10.0  LAMBDA=0.5
      70             : 
      71             : td_pd: TD_PRODUCT_DISTRIBUTION DISTRIBUTIONS=td_uni,td_exp
      72             : ```
      73             : 
      74             : 
      75             : */
      76             : //+ENDPLUMEDOC
      77             : 
      78             : class TD_Exponential: public TargetDistribution {
      79             :   std::vector<double> minima_;
      80             :   std::vector<double> lambda_;
      81             : public:
      82             :   static void registerKeywords(Keywords&);
      83             :   explicit TD_Exponential(const ActionOptions& ao);
      84             :   double getValue(const std::vector<double>&) const override;
      85             : };
      86             : 
      87             : 
      88             : PLUMED_REGISTER_ACTION(TD_Exponential,"TD_EXPONENTIAL")
      89             : 
      90             : 
      91          10 : void TD_Exponential::registerKeywords(Keywords& keys) {
      92          10 :   TargetDistribution::registerKeywords(keys);
      93          10 :   keys.add("compulsory","MINIMUM","The minimum of the exponential distribution.");
      94          10 :   keys.add("compulsory","LAMBDA","The lambda parameter of the exponential distribution given as positive number.");
      95          10 :   keys.use("WELLTEMPERED_FACTOR");
      96          10 :   keys.use("SHIFT_TO_ZERO");
      97          10 :   keys.use("NORMALIZE");
      98          10 : }
      99             : 
     100             : 
     101           8 : TD_Exponential::TD_Exponential(const ActionOptions& ao):
     102             :   PLUMED_VES_TARGETDISTRIBUTION_INIT(ao),
     103          16 :   minima_(0),
     104           8 :   lambda_(0) {
     105           8 :   parseVector("MINIMUM",minima_);
     106           8 :   parseVector("LAMBDA",lambda_);
     107          16 :   for(unsigned int k=0; k<lambda_.size(); k++) {
     108           8 :     if(lambda_[k] < 0.0) {
     109           0 :       plumed_merror(getName()+": the value given in LAMBDA should be positive.");
     110             :     }
     111             :   }
     112             : 
     113             : 
     114           8 :   setDimension(minima_.size());
     115           8 :   if(getDimension()>1) {
     116           0 :     plumed_merror(getName()+": only defined for one dimension, for multiple dimensions it should be used in combination with the TD_PRODUCT_DISTRIBUTION action.");
     117             :   }
     118           8 :   if(lambda_.size()!=getDimension()) {
     119           0 :     plumed_merror(getName()+": the LAMBDA keyword does not match the given dimension in MINIMUM");
     120             :   }
     121           8 :   checkRead();
     122           8 : }
     123             : 
     124             : 
     125        1308 : double TD_Exponential::getValue(const std::vector<double>& argument) const {
     126             :   double value = 1.0;
     127        2616 :   for(unsigned int k=0; k<argument.size(); k++) {
     128        1308 :     double arg = (argument[k]-minima_[k])*lambda_[k];
     129        1308 :     if(arg<0.0) {
     130           0 :       plumed_merror(getName()+": the exponential distribution is not defined for values less that ones given in MINIMUM");
     131             :     }
     132        1308 :     value *= lambda_[k]*exp(-arg);
     133             :   }
     134        1308 :   return value;
     135             : }
     136             : 
     137             : 
     138             : 
     139             : }
     140             : }