/// <summary>
/// See <see cref="IPcgBetaParameterCalculation.CalculateBeta(PcgAlgorithmBase)"/>.
/// </summary>
public double CalculateBeta(PcgAlgorithmBase pcg)
{
double nominator = pcg.ResDotPrecondRes - pcg.PrecondResidual.DotProduct(residualOld);
residualOld.CopyFrom(pcg.Residual);
return((nominator > 0.0) ? nominator / pcg.ResDotPrecondResOld : 0.0);
}
/// <summary>
/// See <see cref="IPcgResidualUpdater.UpdateResidual(PcgAlgorithmBase, IVector)"/>
/// </summary>
public void UpdateResidual(PcgAlgorithmBase pcg, IVector residual)
{
//TODO: perhaps this should be done in an Initialize() method
if (numIterationsBeforeCorrection == int.MinValue)
{
numIterationsBeforeCorrection = (int)Math.Floor(Math.Sqrt(pcg.Rhs.Length));
}
if ((pcg.Iteration % numIterationsBeforeCorrection == 0) && (pcg.Iteration != 0)) //The first iteration uses the correct residual.
{
// Calculate the exact residual: r = b - A * x
ExactResidual.Calculate(pcg.Matrix, pcg.Rhs, pcg.Solution, residual);
}
else
{
// Normally the residual vector is updated as: r = r - α * A*d
residual.AxpyIntoThis(pcg.MatrixTimesDirection, -pcg.StepSize);
}
}
public void Initialize(PcgAlgorithmBase pcg) => denominator = Math.Sqrt(pcg.Rhs.Norm2());
public double EstimateResidualNormRatio(PcgAlgorithmBase pcg) => Math.Sqrt(pcg.ResDotPrecondRes) / denominator;
/// <summary>
/// See <see cref="IPcgResidualUpdater.UpdateResidual(PcgAlgorithmBase, IVector)"/>
/// </summary>
public void UpdateResidual(PcgAlgorithmBase pcg, IVector residual)
{
// Normally the residual vector is updated as: r = r - α * A*d
residual.AxpyIntoThis(pcg.MatrixTimesDirection, -pcg.StepSize);
}
/// <summary>
/// See <see cref="IPcgBetaParameterCalculation.Initialize(PcgAlgorithmBase)"/>.
/// </summary>
public void Initialize(PcgAlgorithmBase pcg)
{
} // Do nothing
/// <summary> /// See <see cref="IPcgBetaParameterCalculation.CalculateBeta(PcgAlgorithmBase)"/>. /// </summary> public double CalculateBeta(PcgAlgorithmBase pcg) => pcg.ResDotPrecondRes / pcg.ResDotPrecondResOld;
/// <summary> /// See <see cref="IPcgResidualConvergence.Initialize(PcgAlgorithmBase)"/> /// </summary> public void Initialize(PcgAlgorithmBase pcg) => denominator = Math.Sqrt(pcg.ResDotPrecondRes);
/// <summary> /// See <see cref="IPcgBetaParameterCalculation.Initialize(IVectorView)"/>. /// </summary> public void Initialize(PcgAlgorithmBase pcg) => residualOld = pcg.Residual.Copy();
