/// <summary>
/// performs one timestep
/// </summary>
/// <param name="dt">size of timestep</param>
public override double Perform(double dt)
{
using (var tr = new ilPSP.Tracing.FuncTrace()) {
if (TimeStepConstraints != null)
{
dt = CalculateTimeStep();
}
double[][] k = new double[m_Scheme.Stages][];
for (int i = 0; i < m_Scheme.Stages; i++)
{
k[i] = new double[Mapping.LocalLength];
}
double[] y0 = new double[Mapping.LocalLength];
DGCoordinates.CopyTo(y0, 0);
// logging
tr.Info("Runge-Kutta Scheme with " + m_Scheme.Stages + " stages.");
double time0 = m_Time;
tr.Info("time = " + time0 + ", dt = " + dt);
// berechne k[0]
ComputeChangeRate(k[0], m_Time, 0);// invokes MPI communication
for (int s = 1; s < m_Scheme.Stages; s++)
{
PerformStage(y0, s, k, dt);
m_Time = time0 + m_Scheme.c[s] * dt;
ComputeChangeRate(k[s], m_Time, m_Scheme.c[s] * dt);// invokes MPI communication
}
// next timestep
DGCoordinates.Clear();
DGCoordinates.CopyFrom(y0, 0);
Array.Clear(y0, 0, y0.Length);
for (int s = 0; s < m_Scheme.Stages; s++)
{
if (m_Scheme.b[s] != 0.0)
{
BLAS.daxpy(y0.Length, -m_Scheme.b[s] * dt, k[s], 1, y0, 1);
}
}
DGCoordinates.axpy <double[]>(y0, 1.0);
base.ApplyFilter(dt);
m_Time = time0 + dt;
}
return(dt);
}
protected override double[] ComputesUpdatedDGCoordinates(double[] completeChangeRate)
{
double[] y0 = new double[Mapping.LocalLength];
DGCoordinates.CopyTo(y0, 0);
DGCoordinates.axpy <double[]>(completeChangeRate, -1);
// Speciality for IBM: Do the extrapolation
speciesMap.Agglomerator.Extrapolate(DGCoordinates.Mapping);
double[] upDGC = DGCoordinates.ToArray();
upDGC = OrderValuesBySgrd(upDGC);
// DGCoordinates should be untouched after calling this method
DGCoordinates.Clear();
DGCoordinates.CopyFrom(y0, 0);
return(upDGC);
}