Page MenuHomec4science
Files F62825439

RungeKuttaOrder2.cpp
No OneTemporary
Actions

File Metadata

Created
Wed, May 15, 22:20

RungeKuttaOrder2.cpp
View Options

#include "RungeKuttaOrder2.h"
/**
* \brief Constructor inherited from the RungeKutta class (also inherited from VectorialODE)
* @param input : Input object containing all variables needed to solve the ODE.
* @param solution : Output object where we will store the solution.
*/
RungeKuttaOrder2::RungeKuttaOrder2(Input &input, Solution& solution) : RungeKutta(input, solution) {}
/**
* \brief Method allowing the implementation of Runge-Kutta method 2 step.
* This method is one of the several definition of the virtual inherited method.
* There are no arguments as all information needed are stored and are accessible in the input object.
* @return Void return as the solution is stored in the solution object.
*/
void RungeKuttaOrder2::SolveVectorialODE() {
//Declaration and initialisation to 0 for all vector we need to solve the system
vector<double> tmp1 = GetColumnsOfMatrix(input->GetInitialConditionMatrix(), 0); //Set the initial condition to 0 and tmp_solution is the vector where the solution will be stored for each iteration.
vector<double> tmp2(input->GetDimension(),0);
vector<double> kutta1(input->GetDimension(),0);
vector<double> kutta2(input->GetDimension(),0);
vector<double> store(input->GetDimension(),0);
solution->ModifySolutionByColumns(tmp1, 0); //Definition of the initial solution with the initial condition
int position_to_write = 1; //Integer defining the position of the column of solution matrix where output is written
const double timestep = input->GetTimestep(); //Get the timestep and store it
const double overall_timestep = input->GetNumberSteps(); //Get the overall number of timestep we will do and store it
for (int i = 1; i < overall_timestep; ++i) { // Solve the system for a fixed number of time steps. Runge-Kutta method needs the timestep i-1 to interpolate so this method will integrate it
kutta1 = AddTwoVector(MultiplyWithVectorByRight(input->GetChangingMatrix(),tmp1), GetColumnsOfMatrix(input->GetPastStepMatrix(), i));
tmp2 = GetColumnsOfMatrix(input->GetPastStepMatrix(), 1 + i);
store = MultiplyVectorAndScalar(AddTwoVector(tmp2, GetColumnsOfMatrix(input->GetPastStepMatrix(), i)),0.5); //Interpolating
kutta2 = AddTwoVector(MultiplyWithVectorByRight((input->GetChangingMatrix()), AddTwoVector(tmp1, MultiplyVectorAndScalar(kutta1, (timestep / 2)))), store);
tmp1 = AddTwoVector(tmp1, MultiplyVectorAndScalar(kutta2, (timestep))); //Apply the definition of the Runge-Kutta method 1 step : https://fr.wikipedia.org/wiki/M%C3%A9thodes_de_Runge-Kutta
if(i%input->GetWriteOutputTimestep()==0.0) { // write output for each print time step.
solution->ModifySolutionByColumns(tmp1, position_to_write);
position_to_write++;
}
}
}

Event Timeline

c4science · Help