Chaste  Release::3.4
GRL1IvpOdeSolver.cpp
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36 /*
37 Megan E. Marsh, Raymond J. Spiteri
38 Numerical Simulation Laboratory
39 University of Saskatchewan
40 December 2011
41 Partial support provided by research grants from the National
42 Science and Engineering Research Council (NSERC) of Canada
43 and the MITACS/Mprime Canadian Network of Centres of Excellence.
44 */
45 #include <cmath>
46 #include "GRL1IvpOdeSolver.hpp"
47 
49  double timeStep,
50  double time,
51  std::vector<double>& rCurrentYValues,
52  std::vector<double>& rNextYValues)
53 {
54  /*
55  * Apply GRL1 first-order method for each time step in AbstractOneStepIvpSolver.
56  * Calculates a vector containing the next Y value from the current one for each
57  * equation in the system.
58  */
59  const double delta = 1.0e-8; // The step for numerical Jacobian calculation
60 
61  const unsigned num_equations = pAbstractOdeSystem->GetNumberOfStateVariables();
62 
63  if (mEvalF.size() != num_equations)
64  {
65  mEvalF.resize(num_equations);
66  mPartialF.resize(num_equations);
67  mTemp.resize(num_equations);
68  }
69 
70  double tempY;
71 
72  pAbstractOdeSystem->EvaluateYDerivatives(time, rCurrentYValues, mEvalF);
73  for (unsigned i=0; i<num_equations; i++)
74  {
75  tempY= rCurrentYValues[i];
76  rCurrentYValues[i]=tempY+delta;
77  pAbstractOdeSystem->EvaluateYDerivatives(time, rCurrentYValues, mTemp);
78  mPartialF[i]=(mTemp[i]-mEvalF[i])/delta;
79  rCurrentYValues[i]=tempY;
80  }
81  // New solution
82  for (unsigned i=0; i<num_equations; i++)
83  {
84  // std::cout<<"Partial F"<< mPartialF[i]<<std::endl;
85  if(fabs(mPartialF[i])<delta)
86  {
87  rNextYValues[i]=rCurrentYValues[i]+mEvalF[i]*timeStep;
88  }
89  else
90  {
91  rNextYValues[i]=rCurrentYValues[i]+(mEvalF[i]/mPartialF[i])*(exp(mPartialF[i]*timeStep)-1);
92  }
93 
94  }
95 }
96 
97 
98 // Serialization for Boost >= 1.36
virtual void EvaluateYDerivatives(double time, const std::vector< double > &rY, std::vector< double > &rDY)=0
void CalculateNextYValue(AbstractOdeSystem *pAbstractOdeSystem, double timeStep, double time, std::vector< double > &rCurrentYValues, std::vector< double > &rNextYValues)
std::vector< double > mEvalF
std::vector< double > mPartialF
#define CHASTE_CLASS_EXPORT(T)
std::vector< double > mTemp