public QuadRuleFactory(Context context, LevelSetTracker tracker, int maxLevels, int minLevels)
{
this.context = context;
this.tracker = tracker;
this.maxLevels = maxLevels;
this.minLevels = minLevels;
baseVertexSet = new NestedVertexSet(context.Grid.SpatialDimension);
double[,] vertices = context.Grid.GridSimplex.Vertices;
int verticesPerCell = vertices.GetLength(0);
int[] polyhedronVertices = new int[verticesPerCell];
for (int i = 0; i < verticesPerCell; i++)
{
double[] vertex = ArrayTools.GetRow(vertices, i);
polyhedronVertices[i] = baseVertexSet.RegisterVertex(vertex);
}
subdivisionTree = new SimplexSubdivisionTree(context.Grid.GridSimplex, baseVertexSet, polyhedronVertices);
for (int i = 0; i < minLevels; i++)
{
subdivisionTree.Subdivide(baseVertexSet, false);
}
subdivisionTree.SetSavePoint();
}
/// <summary>
/// applies this transformation to a series of vectors
/// </summary>
public double[,] Transform(double[,] vtx)
{
if (vtx.GetLength(1) != DomainDimension)
{
throw new ArgumentException("spatial dimension mismatch");
}
int L = vtx.GetLength(0);
var ret = new double[L, CodomainDimension];
double[] x = new double[DomainDimension];
for (int l = 0; l < L; l++)
{
ArrayTools.GetRow(vtx, l, x);
var yl = Transform(x);
ret.SetRow(l, yl);
}
return(ret);
}
/// <summary>
/// Computes the projection of all
/// <see cref="SpatialDimension"/>-dimensional basis polynomials in
/// <paramref name="basis"/> onto this line segment and stores the
/// result in <see cref="ProjectedPolynomialCoefficients"/>
/// </summary>
/// <param name="basis">
/// A basis containing the polynomials to be projected
/// </param>
/// <remarks>
/// Don't ask me (B. Müller) how it works, so please don't touch it. I
/// remember that I coded it but even at that time, I didn't fully
/// understand <b>why</b> it works.
/// </remarks>
public void ProjectBasisPolynomials(Basis basis)
{
int NoOfRefElm = 1;
int iKref = Array.IndexOf(basis.GridDat.iGeomCells.RefElements, this.m_Kref);
int noOfPolynomials = basis.Polynomials[iKref].Count;
int noOfCoefficientsPerDimension = basis.Degree + 1;
MultidimensionalArray[] T = new MultidimensionalArray[SpatialDimension];
ProjectedPolynomialCoefficients = MultidimensionalArray.Create(NoOfRefElm, noOfPolynomials, noOfCoefficientsPerDimension);
// Construct transformations
for (int d = 0; d < SpatialDimension; d++)
{
double a = 0.5 * (End[d] - Start[d]);
double b = 0.5 * (Start[d] + End[d]);
T[d] = MultidimensionalArray.Create(noOfCoefficientsPerDimension, noOfCoefficientsPerDimension);
for (int i = 0; i < noOfCoefficientsPerDimension; i++)
{
for (int j = 0; j < noOfCoefficientsPerDimension; j++)
{
if (i > j)
{
continue;
}
T[d][i, j] = j.Choose(i) * Math.Pow(a, i) * Math.Pow(b, j - i);
}
}
}
{
for (int p = 0; p < noOfPolynomials; p++)
{
Polynomial currentPolynomial = basis.Polynomials[iKref][p];
double[] coefficients = new double[noOfCoefficientsPerDimension];
// Transform coefficients to D-dimensional "matrix"
MultidimensionalArray originalCoefficients = MultidimensionalArray.Create(
Enumerable.Repeat(noOfCoefficientsPerDimension, SpatialDimension).ToArray());
for (int j = 0; j < currentPolynomial.Coeff.Length; j++)
{
int[] exponents = ArrayTools.GetRow(currentPolynomial.Exponents, j);
originalCoefficients[exponents] += currentPolynomial.Coeff[j];
}
// Do projection
switch (SpatialDimension)
{
case 1:
T[0].GEMV(1.0, originalCoefficients.Storage, 0.0, coefficients);
break;
case 2:
MultidimensionalArray coefficientMatrix =
MultidimensionalArray.Create(noOfCoefficientsPerDimension, noOfCoefficientsPerDimension);
coefficientMatrix.Set(originalCoefficients);
coefficientMatrix = T[1] * (T[0] * coefficientMatrix).TransposeInPlace();
// Only left upper triangle can possibly be populated
for (int i = 0; i < noOfCoefficientsPerDimension; i++)
{
for (int j = 0; j < i + 1; j++)
{
coefficients[i] += coefficientMatrix[i - j, j];
}
}
break;
case 3:
MultidimensionalArray matrix = MultidimensionalArray.Create(
noOfCoefficientsPerDimension, noOfCoefficientsPerDimension);
MultidimensionalArray[] Ty = new MultidimensionalArray[noOfCoefficientsPerDimension];
for (int i = 0; i < noOfCoefficientsPerDimension; i++)
{
matrix.Set(originalCoefficients.ExtractSubArrayShallow(-1, -1, i));
Ty[i] = T[1] * (T[0] * matrix).TransposeInPlace();
}
// Only left upper triangle can possibly be populated
MultidimensionalArray tempCoefficients = MultidimensionalArray.Create(noOfCoefficientsPerDimension, Ty[0].NoOfRows);
for (int i = 0; i < Ty[0].NoOfRows; i++)
{
for (int j = 0; j < i + 1; j++)
{
int index = i - j;
for (int k = 0; k < noOfCoefficientsPerDimension; k++)
{
tempCoefficients[k, i] += Ty[k][index, j];
}
}
}
MultidimensionalArray transformedTempCoefficients = T[2] * tempCoefficients;
for (int i = 0; i < noOfCoefficientsPerDimension; i++)
{
for (int j = 0; j < i + 1; j++)
{
coefficients[i] += transformedTempCoefficients[i - j, j];
}
}
break;
default:
throw new ApplicationException("Invalid spatial dimension");
}
ProjectedPolynomialCoefficients.ExtractSubArrayShallow(0, p, -1).AccVector(1.0, coefficients);
}
}
}
public QuadRule GetCutCellQuadRule(LevelSet levelSet, int baseOrder, int cell)
{
// Build tree
subdivisionTree.ResetToSavePoint();
NestedVertexSet currentSet = baseVertexSet;
for (int i = minLevels; i < maxLevels; i++)
{
if (currentSet.LocalNumberOfVertices == 0)
{
// No new vertices were added during last subdivision
break;
}
NodeSetController.NodeSetContainer nsc = context.NSC.CreateContainer(currentSet.Vertices, -1.0);
uint lh = context.NSC.LockNodeSetFamily(nsc);
MultidimensionalArray levelSetValues = MultidimensionalArray.Create(1, nsc.NodeSet.GetLength(0));
levelSet.Evaluate(cell, 1, 0, levelSetValues);
context.NSC.UnlockNodeSetFamily(lh);
subdivisionTree.ReadLevelSetValues(levelSetValues.ExtractSubArrayShallow(0, -1));
currentSet = new NestedVertexSet(currentSet);
subdivisionTree.Subdivide(currentSet, true);
}
// Read level set values of leaves (only if IsCut is used!)
if (currentSet.Vertices != null)
{
NodeSetController.NodeSetContainer nsc2 = context.NSC.CreateContainer(currentSet.Vertices, -1.0);
uint lh2 = context.NSC.LockNodeSetFamily(nsc2);
MultidimensionalArray levelSetValues2 = MultidimensionalArray.Create(1, nsc2.NodeSet.GetLength(0));
levelSet.Evaluate(cell, 1, 0, levelSetValues2);
context.NSC.UnlockNodeSetFamily(lh2);
subdivisionTree.ReadLevelSetValues(levelSetValues2.ExtractSubArrayShallow(0, -1));
}
// Construct rule
List <double[]> nodes = new List <double[]>();
List <double> weights = new List <double>();
foreach (SimplexSubdivisionTree.Node leave in subdivisionTree.Leaves)
{
double det = leave.TransformationFromRoot.Matrix.Determinat();
QuadRule rule;
if (leave.IsCut)
{
rule = GetStandardQuadRule(baseOrder);
}
else
{
rule = GetStandardQuadRule(1);
}
for (int i = 0; i < rule.NoOfNodes; i++)
{
double[] vertex = ArrayTools.GetRow(rule.Nodes, i);
nodes.Add(leave.TransformationFromRoot.Transform(vertex));
weights.Add(det * rule.Weights[i]);
}
}
QuadRule result = new QuadRule();
result.Nodes = NodesToRectangularArray(nodes);
result.Weights = weights.ToArray();
return(result);
}
