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Group15/pcsc_VectorialODE_group15/BashforthFirstStep.cpp
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BashforthFirstStep.cpp
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#include "BashforthFirstStep.h"
/**
* \brief Constructor inherited from the Bashforth 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.
*/
BashforthFirstStep::BashforthFirstStep(Input &input, Solution& solution) : Bashforth(input, solution) {}
/**
* \brief Method allowing the implementation of Adam-Bashforth method 1 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 BashforthFirstStep::SolveVectorialODE() {
vector<double> tmp = 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> tmp_solution = tmp; //Definition of the temporary vector storing for each step the solution
solution->ModifySolutionByColumns(tmp, 0); //Definition of the initial solution with the initial condition
vector<double> past_solution = GetColumnsOfMatrix(input->GetFunctionMatrix(),0); //Vector (i-1) at each iteration storing the function defining the system
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
int position_to_write = 1; //Integer defining the position of the column of solution matrix where output is written
for (int i = 1; i < overall_timestep; i++) { // Solve the system for a fixed number of time steps.
tmp_solution = AddTwoVector(AddTwoVector(MultiplyWithVectorByRight(Multiply(input->GetCoefficientMatrix(), timestep),tmp),(MultiplyVectorAndScalar(tmp,1.0))), MultiplyVectorAndScalar(past_solution,timestep)); //Apply the definition of the Adam-Bashforth method 1 step : https://en.wikipedia.org/wiki/Linear_multistep_method#Adams%E2%80%93Bashforth_methods
if (i%input->GetWriteOutputTimestep()==0.0) { // write output for each print time step.
solution->ModifySolutionByColumns(tmp_solution, position_to_write);
position_to_write++;
}
// Update the several variables to do a new step
tmp = tmp_solution;
past_solution = GetColumnsOfMatrix(input->GetFunctionMatrix(),i);
}
}
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