/// <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);
}
private void UpdateDirectionVector(IVectorView preconditionedResidual, IVector direction)
{
// d = s - sum(β_i * d_i), 0 <= i < currentIteration
// β_i = (s * q_i) / (d_i * q_i)
direction.CopyFrom(preconditionedResidual);
for (int i = 0; i < reorthoCache.Directions.Count; ++i)
{
double beta = preconditionedResidual.DotProduct(reorthoCache.MatrixTimesDirections[i])
/ reorthoCache.DirectionsTimesMatrixTimesDirections[i];
direction.AxpyIntoThis(reorthoCache.Directions[i], -beta);
}
}
internal static void CsrTransTimesVector(int numCsrRows, double[] csrValues, int[] csrRowOffsets, int[] csrColIndices,
IVectorView lhs, IVector rhs)
{
var temp = new double[rhs.Length];
CsrTransTimesVector(numCsrRows, csrValues, csrRowOffsets, csrColIndices, lhs, temp);
rhs.CopyFrom(Vector.CreateFromArray(temp));
// The following requires a lot of indexing into the rhs vector.
//// A^T * x = linear combination of columns of A^T = rows of A, with the entries of x as coefficients
//for (int i = 0; i < numCsrRows; ++i)
//{
// double scalar = lhs[i];
// int rowStart = csrRowOffsets[i]; //inclusive
// int rowEnd = csrRowOffsets[i + 1]; //exclusive
// for (int k = rowStart; k < rowEnd; ++k)
// {
// rhs.Set(csrColIndices[k], rhs[csrColIndices[k]] + scalar * csrValues[k]);
// }
//}
}
/// <summary> /// See <see cref="IPreconditioner.SolveLinearSystem(Vector)"/>. /// </summary> /// <remarks> /// This method works for all dimensions of the preconditioner matrix and the right hand side vector. This way the user /// doesn't have to define the dimensions of the linear system, which is useful when testing or benchmarking, at the /// expense of little extra safety. /// </remarks> public void SolveLinearSystem(IVectorView rhsVector, IVector lhsVector) => lhsVector.CopyFrom(rhsVector);
public void ExtractVectorSubdomainFromGlobal(ISubdomain subdomain, IVectorView globalVector, IVector subdomainVector)
{
Debug.Assert(subdomain == this.subdomain);
subdomainVector.CopyFrom(globalVector);
}