private IVector CalculateRhsImplicit(ILinearSystem linearSystem, bool addRhs)
{
int id = linearSystem.Subdomain.ID;
capacityTimesTemperature[id] = provider.MassMatrixVectorProduct(linearSystem.Subdomain, temperature[id]);
conductivityTimesTemperature[id] = provider.DampingMatrixVectorProduct(linearSystem.Subdomain, temperature[id]);
IVector rhsResult = rhsPrevious[id].LinearCombination(1 - beta, rhs[id], beta);
rhsResult.AxpyIntoThis(capacityTimesTemperature[id], 1 / timeStep);
rhsResult.AxpyIntoThis(conductivityTimesTemperature[id], -(1 - beta));
rhsPrevious[id] = rhs[id];
return(rhsResult);
}
/// <summary>
/// Calculates the initial approximation to the linear system's solution vector, by using a series of conjugate direction
/// vectors that have been stored previously by PCG during the solution of other linear systems with the same matrix.
/// This method should be used to solve linear systems with different right hand side vectors and the same matrix.
/// </summary>
/// <param name="rhsNew">The right hand side vector of the new linear system.</param>
/// <param name="initialSolution">
/// The initial approximation to the solution vector, which PCG will improve. It will be overwritten by this method.
/// </param>
/// <param name="isSolutionZero">
/// Set to true if <paramref name="initialSolution"/> is the zero vector, to avoid clearing it.
/// </param>
/// <exception cref="InvalidOperationException">Thrown if there are no direction vectors stored yet.</exception>
public void CalculateInitialSolutionFromStoredDirections(IVectorView rhsNew, IVector initialSolution,
bool isSolutionZero)
{
if (reorthoCache.Directions.Count < 1)
{
throw new InvalidOperationException("There are no direction vectors stored.");
}
if (!isSolutionZero)
{
initialSolution.Clear();
}
//TODO: An implementation by G. Stavroulakis discarded the last stored direction vector at this point. Why?
//reorthoCache.RemoveNewDirectionVectorData(1);
// x0 = D_nd * x_d, x_d = inv(Q_nd * D_nd) * D_nd^T * b
// D_nd = [d_1 ... d_nd], Q_nd = A * D_nd = [q_1 ... q_nd], Q_nd * D_nd = diag([d1*A*d1 ... d_nd*A*d_nd])
for (int i = 0; i < reorthoCache.Directions.Count; ++i)
{
// x_d[i] = 1/(d_i * q_i) * (d_i * b)
double xd = reorthoCache.Directions[i].DotProduct(rhsNew) / reorthoCache.DirectionsTimesMatrixTimesDirections[i];
Debug.Assert(!double.IsNaN(xd));
Debug.Assert(!double.IsPositiveInfinity(xd));
Debug.Assert(!double.IsNegativeInfinity(xd));
// x0 += d_i * x_d[i]
initialSolution.AxpyIntoThis(reorthoCache.Directions[i], xd);
}
}
/// <summary>
/// Gram–Schmidt orthogonalization to the stored vectors, without normalization.
/// </summary>
/// <param name="v">The vector to reorthogonalize. It will be overwritten with the result. If there are no stored
/// vectors, it will remain unchanged without being copied.</param>
internal void Reorthogonalize(IVector v)
{
// reorthogonalize 1 by 1
foreach (var p in store)
{
// we don't have to normalize since it is explicitly done in the code and so we don't need to redo it
v.AxpyIntoThis(p, -(v.DotProduct(p))); // orthogonalize to each stored vector
}
}
private IVector CalculateRhsImplicit(ILinearSystem linearSystem, bool addRhs)
{
//TODO: what is the meaning of addRhs? Do we need this when solving dynamic thermal equations?
// result = (1-b)* rhsPrevious + beta * rhs + 1/dt * 1stOrderMatrix * unknown - (1-b) * 0thOrderMatrix * unknown
int id = linearSystem.Subdomain.ID;
firstOrderMatrixTimesUnknown[id] = provider.MassMatrixVectorProduct(linearSystem.Subdomain, unknown[id]);
zerothOrderMatrixTimesUnknown[id] = provider.DampingMatrixVectorProduct(linearSystem.Subdomain, unknown[id]);
IVector rhsResult = rhsPrevious[id].LinearCombination(1 - beta, rhs[id], beta);
rhsResult.AxpyIntoThis(firstOrderMatrixTimesUnknown[id], 1 / timeStep);
rhsResult.AxpyIntoThis(zerothOrderMatrixTimesUnknown[id], -(1 - beta));
rhsPrevious[id] = rhs[id];
return(rhsResult);
}
private IVector CalculateRhsImplicit(ILinearSystem linearSystem, bool addRhs)
{
//TODO: what is the meaning of addRhs? Do we need this when solving dynamic thermal equations?
// result = (1-b)* rhsPrevious + beta * rhs + 1/dt * Capacity * temperature - (1-b) * Conductivity * temperature
int id = linearSystem.Subdomain.ID;
capacityTimesTemperature[id] = provider.MassMatrixVectorProduct(linearSystem.Subdomain, temperature[id]);
conductivityTimesTemperature[id] = provider.DampingMatrixVectorProduct(linearSystem.Subdomain, temperature[id]);
IVector rhsResult = rhsPrevious[id].LinearCombination(1 - beta, rhs[id], beta);
rhsResult.AxpyIntoThis(capacityTimesTemperature[id], 1 / timeStep);
rhsResult.AxpyIntoThis(conductivityTimesTemperature[id], -(1 - beta));
rhsPrevious[id] = rhs[id];
return(rhsResult);
}
private IVector CalculateRhsImplicit(ILinearSystem linearSystem, int modelNo, bool addRhs)
{
//TODO: what is the meaning of addRhs? Do we need this when solving dynamic thermal equations?
//TODO: stabilizingRhs has not been implemented
// result = -dt(conductuvity*temperature + rhs -dt(stabilizingConductivity*temperature + StabilizingRhs))
int id = linearSystem.Subdomain.ID;
firstOrderMatrixTimesUnknown[modelNo][id] = providers[modelNo].MassMatrixVectorProduct(linearSystem.Subdomain, unknown[modelNo][id]);
secondOrderMatrixTimesUnknown[modelNo][id] = providers[modelNo].DampingMatrixVectorProduct(linearSystem.Subdomain, unknown[modelNo][id]);
IVector rhsResult = rhsPrevious[modelNo][id].LinearCombination(1 - beta, rhs[modelNo][id], beta);
rhsResult.AxpyIntoThis(firstOrderMatrixTimesUnknown[modelNo][id], 1 / timeStep);
rhsResult.AxpyIntoThis(secondOrderMatrixTimesUnknown[modelNo][id], -(1 - beta));
rhsPrevious[modelNo][id] = rhs[modelNo][id];
return(rhsResult);
}
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);
}
}
/// <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 UpdateResidual(CGAlgorithm cg, IVector residual, out double resDotRes)
{
// Update the residual vector normally: r = r - α * A*d
residual.AxpyIntoThis(cg.MatrixTimesDirection, -cg.StepSize);
resDotRes = residual.DotProduct(residual); //TODO: it is weird that this sets resDotRes and cg.ResDotRes
// Check if the CG will converge. TODO: Remove duplicate comutations: this check will also be done by CG later.
double residualNormRatio = convergence.EstimateResidualNormRatio(cg); // let's pray that ICGResidualConvergence does not mutate any fields
bool hasConverged = residualNormRatio <= residualTolerance;
// Avoid premature convergence by calculating th exact residual.
if (hasConverged)
{
// Exact residual: r = b - A * x
ExactResidual.Calculate(cg.Matrix, cg.Rhs, cg.Solution, residual);
// Recalculate the r * r
resDotRes = residual.DotProduct(residual);
}
}
/// <summary>
/// Calculates the initial approximation to the linear system's solution vector, by using a series of conjugate direction
/// vectors that have been stored previously by PCG during the solution of other linear systems with the same matrix.
/// This method should be used to solve linear systems with different right hand side vectors and the same matrix.
/// </summary>
/// <param name="rhsNew">The right hand side vector of the new linear system.</param>
/// <param name="initialSolution">
/// The initial approximation to the solution vector, which PCG will improve. It will be overwritten by this method.
/// </param>
/// <exception cref="InvalidOperationException">Thrown if there are no direction vectors stored yet.</exception>
public void CalculateInitialSolutionFromStoredDirections(IVectorView rhsNew, IVector initialSolution)
{
//TODO: An implementation by G. Stavroulakis discarded the last stored direction vector at this point. Why?
//reorthoCache.RemoveNewDirectionVectorData(1);
// x0 = D_nd * x_d, x_d = inv(Q_nd * D_nd) * D_nd^T * b
// D_nd = [d_1 ... d_nd], Q_nd = A * D_nd = [q_1 ... q_nd], Q_nd * D_nd = diag([d1*A*d1 ... d_nd*A*d_nd])
for (int i = 0; i < ReorthoCache.Directions.Count; ++i)
{
// x_d[i] = (d_i * b) / (d_i * q_i)
double xd = ReorthoCache.Directions[i].DotProduct(rhsNew) / ReorthoCache.DirectionsTimesMatrixTimesDirections[i];
Debug.Assert(!double.IsNaN(xd));
Debug.Assert(!double.IsPositiveInfinity(xd));
Debug.Assert(!double.IsNegativeInfinity(xd));
// x0 += d_i * x_d[i]
initialSolution.AxpyIntoThis(ReorthoCache.Directions[i], xd);
}
}
/// <summary>
/// See <see cref="ICGResidualUpdater.UpdateResidual(CGAlgorithm, IVector, out double)"/>
/// </summary>
public void UpdateResidual(CGAlgorithm cg, IVector residual, out double resDotRes)
{
// Normally the residual vector is updated as: r = r - α * A*d
residual.AxpyIntoThis(cg.MatrixTimesDirection, -cg.StepSize);
resDotRes = residual.DotProduct(residual);
}
/// <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> /// Performs the operation: /// <paramref name="thisVector"/>[i] = <paramref name="thisVector"/>[i] + <paramref name="otherVector"/>[i], for /// 0 <= i < <paramref name="thisVector"/>.<see cref="IIndexable1D.Length"/> /// = <paramref name="otherVector"/>.<see cref="IIndexable1D.Length"/>. /// The resulting vector overwrites the entries of this <see cref="IVector"/> instance. /// </summary> /// <param name="thisVector"> /// A vector with the same <see cref="IIndexable1D.Length"/> as <paramref name="otherVector"/>. /// </param> /// <param name="otherVector"> /// A vector with the same <see cref="IIndexable1D.Length"/> as <paramref name="thisVector"/>. /// </param> /// <exception cref="NonMatchingDimensionsException"> /// Thrown if <paramref name="thisVector"/> and <paramref name="otherVector"/> have different /// <see cref="IIndexable1D.Length"/>. /// </exception> public static void AddIntoThis(this IVector thisVector, IVectorView otherVector) => thisVector.AxpyIntoThis(otherVector, 1.0);
/// <summary> /// Performs the operation: /// <paramref name="thisVector"/>[i] = <paramref name="thisVector"/>[i] - <paramref name="otherVector"/>[i], /// for 0 <= i < <paramref name="thisVector"/>.<see cref="IIndexable1D.Length"/> /// = <paramref name="otherVector"/>.<see cref="IIndexable1D.Length"/>. /// The resulting vector overwrites the entries of this <see cref="IVector"/> instance. /// </summary> /// <param name="thisVector"> /// A vector with the same <see cref="IIndexable1D.Length"/> as <paramref name="otherVector"/>. /// </param> /// <param name="otherVector"> /// A vector with the same <see cref="IIndexable1D.Length"/> as <paramref name="thisVector"/>. /// </param> /// <exception cref="NonMatchingDimensionsException"> /// Thrown if <paramref name="thisVector"/> and <paramref name="otherVector"/> have different /// <see cref="IIndexable1D.Length"/>. /// </exception> public static void SubtractIntoThis(this IVector thisVector, IVectorView otherVector) => thisVector.AxpyIntoThis(otherVector, -1.0);
