public void TestBSplines1DValues()
{
var degree = 3;
var knotValueVector = KnotValueVector;
var parametricCoordinates = ParametricCoordinates;
var bsplines1D = new BSPLines1D(degree, knotValueVector, parametricCoordinates);
bsplines1D.calculateBSPLinesAndDerivatives();
var expectedValues = new double[4, 4]
{
{ 0.8058320948251374, 0.3007502363228445, 0.035940096838251105, 3.3471572805268126E-4 },
{ 0.18718777049037877, 0.5628454528272727, 0.5162916318030126, 0.30510371716505036 },
{ 0.006924348732218876, 0.13041429476462738, 0.39764323219603925, 0.5602562184023526 },
{ 5.5785952265056314E-5, 0.005990016085255392, 0.05012503916269711, 0.13430534870454433 },
};
for (var i = 0; i < 4; i++)
{
for (var j = 0; j < 4; j++)
{
Assert.True(Utilities.AreValuesEqual(expectedValues[i, j], bsplines1D.BSPLineValues[i, j],
Tolerance));
}
}
}
public void TestBSplines1DDerivativeValues()
{
var degree = 3;
var knotValueVector = KnotValueVector;
var parametricCoordinates = ParametricCoordinates;
var bsplines1D = new BSPLines1D(degree, knotValueVector, parametricCoordinates);
bsplines1D.calculateBSPLinesAndDerivatives();
var expectedDerivativeValues = new double[4, 4]
{
{ -23.380841503242923, -12.119957092815207, -2.940468916024088, -0.13016109020350003 },
{ 21.603802526477924, 5.4150528637737025, -6.0593073618049385, -7.4595480014466915 },
{ 1.7553454623559663, 6.214826079340906, 6.979783435056406, 3.6929021828181523 },
{ 0.02169351440903006, 0.49007814970059616, 2.01999284277262, 3.8968069088320396 },
};
for (var i = 0; i < 4; i++)
{
for (var j = 0; j < 4; j++)
{
Assert.True(Utilities.AreValuesEqual(expectedDerivativeValues[i, j], bsplines1D.BSPLineDerivativeValues[i, j],
Tolerance));
}
}
}
/// <summary>
/// Defines an 1D NURBS shape function for an edge element.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="NurbsElement1D"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
/// <param name="edge">The one-dimensional boundary entity that contains the <paramref name="element"/>.</param>
public Nurbs1D(Element element, IList <ControlPoint> controlPoints, Edge edge)
{
GaussQuadrature gauss = new GaussQuadrature();
IList <GaussLegendrePoint3D> gaussPoints = gauss.CalculateElementGaussPoints(edge.Degree, element.Knots.ToArray());
var parametricGaussPointKsi = Vector.CreateZero(edge.Degree + 1);
for (int i = 0; i < edge.Degree + 1; i++)
{
parametricGaussPointKsi[i] = gaussPoints[i].Ksi;
}
var bsplinesKsi = new BSPLines1D(edge.Degree, edge.KnotValueVector, parametricGaussPointKsi);
bsplinesKsi.calculateBSPLinesAndDerivatives();
int supportKsi = edge.Degree + 1;
int numberOfElementControlPoints = supportKsi;
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
for (int i = 0; i < supportKsi; i++)
{
double sumKsi = 0;
double sumdKsi = 0;
for (int j = 0; j < numberOfElementControlPoints; j++)
{
int index = controlPoints[j].ID;
sumKsi += bsplinesKsi.BSPLineValues[index, i] * controlPoints[j].WeightFactor;
sumdKsi += bsplinesKsi.BSPLineDerivativeValues[index, i] * controlPoints[j].WeightFactor;
}
for (int j = 0; j < numberOfElementControlPoints; j++)
{
int indexKsi = controlPoints[j].ID;
NurbsValues[j, i] = bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[j].WeightFactor / sumKsi;
NurbsDerivativeValuesKsi[j, i] = controlPoints[j].WeightFactor * (bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsi -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsi) / Math.Pow(sumKsi, 2);
}
}
}
public void TestBSplines1DPartitionOfUnity()
{
var degree = 3;
var knotValueVector = KnotValueVector;
var parametricCoordinates = ParametricCoordinates;
var bsplines1D = new BSPLines1D(degree, knotValueVector, parametricCoordinates);
bsplines1D.calculateBSPLinesAndDerivatives();
for (var p = 0; p < 4; p++)
{
var sum = 0.0;
for (var f = 0; f < bsplines1D.BSPLineValues.GetLength(0); f++)
{
sum += bsplines1D.BSPLineValues[f, p];
}
Assert.True(Utilities.AreValuesEqual(1.0, sum, Tolerance));
}
}
/// <summary>
/// Two-dimensional T-spline shape functions from Bezier extraction for <see cref="TSplineKirchhoffLoveShellElementMaterial"/>.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="TSplineKirchhoffLoveShellElementMaterial"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
public ShapeTSplines2DFromBezierExtraction(TSplineKirchhoffLoveShellElementMaterial element, ControlPoint[] controlPoints)
{
GaussQuadrature gauss = new GaussQuadrature();
IList <GaussLegendrePoint3D> gaussPoints = gauss.CalculateElementGaussPoints(element.DegreeKsi, element.DegreeHeta,
new List <Knot>
{
new Knot()
{
ID = 0, Ksi = -1, Heta = -1, Zeta = 0
},
new Knot()
{
ID = 1, Ksi = -1, Heta = 1, Zeta = 0
},
new Knot()
{
ID = 2, Ksi = 1, Heta = -1, Zeta = 0
},
new Knot()
{
ID = 3, Ksi = 1, Heta = 1, Zeta = 0
}
});
var parametricGaussPointKsi = Vector.CreateZero(element.DegreeKsi + 1);
for (int i = 0; i < element.DegreeKsi + 1; i++)
{
parametricGaussPointKsi[i] = gaussPoints[i * (element.DegreeHeta + 1)].Ksi;
}
var parametricGaussPointHeta = Vector.CreateZero(element.DegreeHeta + 1);
for (int i = 0; i < element.DegreeHeta + 1; i++)
{
parametricGaussPointHeta[i] = gaussPoints[i].Heta;
}
Vector knotValueVectorKsi = Vector.CreateZero((element.DegreeKsi + 1) * 2);
Vector knotValueVectorHeta = Vector.CreateZero((element.DegreeHeta + 1) * 2);
for (int i = 0; i < element.DegreeKsi + 1; i++)
{
knotValueVectorKsi[i] = -1;
knotValueVectorKsi[element.DegreeKsi + 1 + i] = 1;
}
for (int i = 0; i < element.DegreeHeta + 1; i++)
{
knotValueVectorHeta[i] = -1;
knotValueVectorHeta[element.DegreeHeta + 1 + i] = 1;
}
BSPLines1D bernsteinKsi = new BSPLines1D(element.DegreeKsi, knotValueVectorKsi, parametricGaussPointKsi);
BSPLines1D bernsteinHeta = new BSPLines1D(element.DegreeHeta, knotValueVectorHeta, parametricGaussPointHeta);
bernsteinKsi.calculateBSPLinesAndDerivatives();
bernsteinHeta.calculateBSPLinesAndDerivatives();
int supportKsi = element.DegreeKsi + 1;
int supportHeta = element.DegreeHeta + 1;
var bKsi = MatrixPart(supportKsi, bernsteinKsi.BSPLineValues);
var bdKsi = MatrixPart(supportKsi, bernsteinKsi.BSPLineDerivativeValues);
var bddKsi = MatrixPart(supportKsi, bernsteinKsi.BSPLineSecondDerivativeValues);
var bheta = MatrixPart(supportHeta, bernsteinHeta.BSPLineValues);
var bdheta = MatrixPart(supportHeta, bernsteinHeta.BSPLineDerivativeValues);
var bddheta = MatrixPart(supportHeta, bernsteinHeta.BSPLineSecondDerivativeValues);
var bernsteinShapeFunctions = KroneckerProduct(bKsi, bheta);
Matrix bernsteinShapeFunctionDerivativesKsi = KroneckerProduct(bheta, bdKsi);
Matrix bernsteinShapeFunctionDerivativesHeta = KroneckerProduct(bdheta, bKsi);
Matrix bernsteinShapeFunctionSecondDerivativesKsi = KroneckerProduct(bheta, bddKsi);
Matrix bernsteinShapeFunctionSecondDerivativesHeta = KroneckerProduct(bddheta, bKsi);
Matrix bernsteinShapeFunctionSecondDerivativesKsiHeta = KroneckerProduct(bdheta, bdKsi);
Matrix rationalTSplines = element.ExtractionOperator * bernsteinShapeFunctions;
Matrix rationalTSplineDerivativesKsi = element.ExtractionOperator * bernsteinShapeFunctionDerivativesKsi;
Matrix rationalTSplineDerivativesHeta = element.ExtractionOperator * bernsteinShapeFunctionDerivativesHeta;
Matrix rationalTSplineSecondDerivativesKsi = element.ExtractionOperator * bernsteinShapeFunctionSecondDerivativesKsi;
Matrix rationalTSplineSecondDerivativesHeta = element.ExtractionOperator * bernsteinShapeFunctionSecondDerivativesHeta;
Matrix rationalTSplineSecondDerivativesKsiHeta = element.ExtractionOperator * bernsteinShapeFunctionSecondDerivativesKsiHeta;
TSplineValues = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineDerivativeValuesKsi = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineDerivativeValuesHeta = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineSecondDerivativesValueKsi = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineSecondDerivativesValueHeta = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineSecondDerivativesValueKsiHeta = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
double sumKsiHeta = 0;
double sumdKsiHeta = 0;
double sumKsidHeta = 0;
double sumdKsidKsi = 0;
double sumdHetadHeta = 0;
double sumdKsidHeta = 0;
var index = i * supportHeta + j;
for (int k = 0; k < controlPoints.Length; k++)
{
sumKsiHeta += rationalTSplines[k, index] * controlPoints[k].WeightFactor;
sumdKsiHeta += rationalTSplineDerivativesKsi[k, index] * controlPoints[k].WeightFactor;
sumKsidHeta += rationalTSplineDerivativesHeta[k, index] * controlPoints[k].WeightFactor;
sumdKsidKsi += rationalTSplineSecondDerivativesKsi[k, index] * controlPoints[k].WeightFactor;
sumdHetadHeta += rationalTSplineSecondDerivativesHeta[k, index] * controlPoints[k].WeightFactor;
sumdKsidHeta += rationalTSplineSecondDerivativesKsiHeta[k, index] * controlPoints[k].WeightFactor;
}
for (int k = 0; k < controlPoints.Length; k++)
{
TSplineValues[k, index] = rationalTSplines[k, index] * controlPoints[k].WeightFactor / sumKsiHeta;
TSplineDerivativeValuesKsi[k, index] = (rationalTSplineDerivativesKsi[k, index] * sumKsiHeta -
rationalTSplines[k, index] * sumdKsiHeta) /
Math.Pow(sumKsiHeta, 2) * controlPoints[k].WeightFactor;
TSplineDerivativeValuesHeta[k, index] = (rationalTSplineDerivativesHeta[k, index] * sumKsiHeta -
rationalTSplines[k, index] * sumKsidHeta) /
Math.Pow(sumKsiHeta, 2) * controlPoints[k].WeightFactor;
TSplineSecondDerivativesValueKsi[k, index] = (rationalTSplineSecondDerivativesKsi[k, index] / sumKsiHeta -
2 * rationalTSplineDerivativesKsi[k, index] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplines[k, index] * sumdKsidKsi / Math.Pow(sumKsiHeta, 2) +
2 * rationalTSplines[k, index] * Math.Pow(sumdKsiHeta, 2) /
Math.Pow(sumKsiHeta, 3)) * controlPoints[k].WeightFactor;
TSplineSecondDerivativesValueHeta[k, index] = (rationalTSplineSecondDerivativesHeta[k, index] / sumKsiHeta -
2 * rationalTSplineDerivativesHeta[k, index] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplines[k, index] * sumdHetadHeta /
Math.Pow(sumKsiHeta, 2) +
2 * rationalTSplines[k, index] * Math.Pow(sumKsidHeta, 2) /
Math.Pow(sumKsiHeta, 3)) * controlPoints[k].WeightFactor;
TSplineSecondDerivativesValueKsiHeta[k, index] = (rationalTSplineSecondDerivativesKsiHeta[k, index] / sumKsiHeta -
rationalTSplineDerivativesKsi[k, index] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplineDerivativesHeta[k, index] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplines[k, index] * sumdKsidHeta /
Math.Pow(sumKsiHeta, 2) +
2 * rationalTSplines[k, index] * sumdKsiHeta * sumKsidHeta /
Math.Pow(sumKsiHeta, 3)) *
controlPoints[k].WeightFactor;
}
}
}
}
/// <summary>
/// Two-dimensional T-spline shape functions from Bezier extraction for <see cref="TSplineKirchhoffLoveShellElement"/>.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="TSplineKirchhoffLoveShellElement"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
/// <param name="parametricGaussPointKsi">An <see cref="IVector"/> containing Gauss points of axis Ksi.</param>
/// <param name="parametricGaussPointHeta">An <see cref="IVector"/> containing Gauss points of axis Heta.</param>
public ShapeTSplines2DFromBezierExtraction(TSplineKirchhoffLoveShellElement element, ControlPoint[] controlPoints, Vector parametricGaussPointKsi, Vector parametricGaussPointHeta)
{
Vector knotValueVectorKsi = Vector.CreateZero((element.DegreeKsi + 1) * 2);
Vector knotValueVectorHeta = Vector.CreateZero((element.DegreeHeta + 1) * 2);
for (int i = 0; i < element.DegreeKsi + 1; i++)
{
knotValueVectorKsi[i] = -1;
knotValueVectorKsi[element.DegreeKsi + 1 + i] = 1;
}
for (int i = 0; i < element.DegreeHeta + 1; i++)
{
knotValueVectorHeta[i] = -1;
knotValueVectorHeta[element.DegreeHeta + 1 + i] = 1;
}
BSPLines1D bernsteinKsi = new BSPLines1D(element.DegreeKsi, knotValueVectorKsi, parametricGaussPointKsi);
BSPLines1D bernsteinHeta = new BSPLines1D(element.DegreeHeta, knotValueVectorHeta, parametricGaussPointHeta);
bernsteinKsi.calculateBSPLinesAndDerivatives();
bernsteinHeta.calculateBSPLinesAndDerivatives();
int supportElementKsi = element.DegreeKsi + 1;
int supportElementHeta = element.DegreeHeta + 1;
int supportKsi = parametricGaussPointKsi.Length;
int supportHeta = parametricGaussPointHeta.Length;
var bKsi = MatrixPart(supportElementKsi, supportKsi, bernsteinKsi.BSPLineValues);
var bdKsi = MatrixPart(supportElementKsi, supportKsi, bernsteinKsi.BSPLineDerivativeValues);
var bddKsi = MatrixPart(supportElementKsi, supportKsi, bernsteinKsi.BSPLineSecondDerivativeValues);
var bheta = MatrixPart(supportElementHeta, supportHeta, bernsteinHeta.BSPLineValues);
var bdheta = MatrixPart(supportElementHeta, supportHeta, bernsteinHeta.BSPLineDerivativeValues);
var bddheta = MatrixPart(supportElementHeta, supportHeta, bernsteinHeta.BSPLineSecondDerivativeValues);
var bernsteinShapeFunctions = KroneckerProduct(bKsi, bheta);
Matrix bernsteinShapeFunctionDerivativesKsi = KroneckerProduct(bheta, bdKsi);
Matrix bernsteinShapeFunctionDerivativesHeta = KroneckerProduct(bdheta, bKsi);
Matrix bernsteinShapeFunctionSecondDerivativesKsi = KroneckerProduct(bheta, bddKsi);
Matrix bernsteinShapeFunctionSecondDerivativesHeta = KroneckerProduct(bddheta, bKsi);
Matrix bernsteinShapeFunctionSecondDerivativesKsiHeta = KroneckerProduct(bdheta, bdKsi);
Matrix rationalTSplines = element.ExtractionOperator * bernsteinShapeFunctions;
Matrix rationalTSplineDerivativesKsi = element.ExtractionOperator * bernsteinShapeFunctionDerivativesKsi;
Matrix rationalTSplineDerivativesHeta = element.ExtractionOperator * bernsteinShapeFunctionDerivativesHeta;
Matrix rationalTSplineSecondDerivativesKsi = element.ExtractionOperator * bernsteinShapeFunctionSecondDerivativesKsi;
Matrix rationalTSplineSecondDerivativesHeta = element.ExtractionOperator * bernsteinShapeFunctionSecondDerivativesHeta;
Matrix rationalTSplineSecondDerivativesKsiHeta = element.ExtractionOperator * bernsteinShapeFunctionSecondDerivativesKsiHeta;
TSplineValues = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineDerivativeValuesKsi = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineDerivativeValuesHeta = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineSecondDerivativesValueKsi = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineSecondDerivativesValueHeta = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
TSplineSecondDerivativesValueKsiHeta = Matrix.CreateZero(controlPoints.Length, supportKsi * supportHeta);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
double sumKsiHeta = 0;
double sumdKsiHeta = 0;
double sumKsidHeta = 0;
double sumdKsidKsi = 0;
double sumdHetadHeta = 0;
double sumdKsidHeta = 0;
var index = i * supportHeta + j;
for (int k = 0; k < controlPoints.Length; k++)
{
sumKsiHeta += rationalTSplines[k, index] * controlPoints[k].WeightFactor;
sumdKsiHeta += rationalTSplineDerivativesKsi[k, index] * controlPoints[k].WeightFactor;
sumKsidHeta += rationalTSplineDerivativesHeta[k, index] * controlPoints[k].WeightFactor;
sumdKsidKsi += rationalTSplineSecondDerivativesKsi[k, index] * controlPoints[k].WeightFactor;
sumdHetadHeta += rationalTSplineSecondDerivativesHeta[k, index] * controlPoints[k].WeightFactor;
sumdKsidHeta += rationalTSplineSecondDerivativesKsiHeta[k, index] * controlPoints[k].WeightFactor;
}
for (int k = 0; k < controlPoints.Length; k++)
{
TSplineValues[k, index] = rationalTSplines[k, index] * controlPoints[k].WeightFactor / sumKsiHeta;
TSplineDerivativeValuesKsi[k, index] = (rationalTSplineDerivativesKsi[k, index] * sumKsiHeta -
rationalTSplines[k, index] * sumdKsiHeta) /
Math.Pow(sumKsiHeta, 2) * controlPoints[k].WeightFactor;
TSplineDerivativeValuesHeta[k, index] = (rationalTSplineDerivativesHeta[k, index] * sumKsiHeta -
rationalTSplines[k, index] * sumKsidHeta) /
Math.Pow(sumKsiHeta, 2) * controlPoints[k].WeightFactor;
TSplineSecondDerivativesValueKsi[k, index] = (rationalTSplineSecondDerivativesKsi[k, index] / sumKsiHeta -
2 * rationalTSplineDerivativesKsi[k, index] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplines[k, index] * sumdKsidKsi / Math.Pow(sumKsiHeta, 2) +
2 * rationalTSplines[k, index] * Math.Pow(sumdKsiHeta, 2) /
Math.Pow(sumKsiHeta, 3)) * controlPoints[k].WeightFactor;
TSplineSecondDerivativesValueHeta[k, index] = (rationalTSplineSecondDerivativesHeta[k, index] / sumKsiHeta -
2 * rationalTSplineDerivativesHeta[k, index] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplines[k, index] * sumdHetadHeta /
Math.Pow(sumKsiHeta, 2) +
2 * rationalTSplines[k, index] * Math.Pow(sumKsidHeta, 2) /
Math.Pow(sumKsiHeta, 3)) * controlPoints[k].WeightFactor;
TSplineSecondDerivativesValueKsiHeta[k, index] = (rationalTSplineSecondDerivativesKsiHeta[k, index] / sumKsiHeta -
rationalTSplineDerivativesKsi[k, index] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplineDerivativesHeta[k, index] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
rationalTSplines[k, index] * sumdKsidHeta /
Math.Pow(sumKsiHeta, 2) +
2 * rationalTSplines[k, index] * sumdKsiHeta * sumKsidHeta /
Math.Pow(sumKsiHeta, 3)) *
controlPoints[k].WeightFactor;
}
}
}
}
/// <summary>
/// Defines 3D NURBS shape functions given the control points.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="NurbsElement3D"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
public Nurbs3D(Element element, ControlPoint[] controlPoints)
{
GaussQuadrature gauss = new GaussQuadrature();
IList <GaussLegendrePoint3D> gaussPoints = gauss.CalculateElementGaussPoints(element.Patch.DegreeKsi, element.Patch.DegreeHeta, element.Patch.DegreeZeta, element.Knots.ToArray());
var parametricGaussPointKsi = Vector.CreateZero(element.Patch.DegreeKsi + 1);
for (int i = 0; i < element.Patch.DegreeKsi + 1; i++)
{
parametricGaussPointKsi[i] = gaussPoints[i * (element.Patch.DegreeZeta + 1) * (element.Patch.DegreeHeta + 1)].Ksi;
}
var parametricGaussPointHeta = Vector.CreateZero(element.Patch.DegreeHeta + 1);
for (int i = 0; i < element.Patch.DegreeHeta + 1; i++)
{
parametricGaussPointHeta[i] = gaussPoints[i * (element.Patch.DegreeZeta + 1)].Heta;
}
var parametricGaussPointZeta = Vector.CreateZero(element.Patch.DegreeZeta + 1);
for (int i = 0; i < element.Patch.DegreeZeta + 1; i++)
{
parametricGaussPointZeta[i] = gaussPoints[i].Zeta;
}
BSPLines1D bsplinesKsi = new BSPLines1D(element.Patch.DegreeKsi, element.Patch.KnotValueVectorKsi, parametricGaussPointKsi);
BSPLines1D bsplinesHeta = new BSPLines1D(element.Patch.DegreeHeta, element.Patch.KnotValueVectorHeta, parametricGaussPointHeta);
BSPLines1D bsplinesZeta = new BSPLines1D(element.Patch.DegreeZeta, element.Patch.KnotValueVectorZeta, parametricGaussPointZeta);
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
bsplinesZeta.calculateBSPLinesAndDerivatives();
int supportKsi = element.Patch.DegreeKsi + 1;
int supportHeta = element.Patch.DegreeHeta + 1;
int supportZeta = element.Patch.DegreeZeta + 1;
int numberOfElementControlPoints = supportKsi * supportHeta * supportZeta;
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsDerivativeValuesZeta = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
for (int k = 0; k < supportZeta; k++)
{
double sumKsiHetaZeta = 0;
double sumdKsiHetaZeta = 0;
double sumKsidHetaZeta = 0;
double sumKsiHetadZeta = 0;
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID / (element.Patch.NumberOfControlPointsHeta * element.Patch.NumberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID % (element.Patch.NumberOfControlPointsHeta * element.Patch.NumberOfControlPointsZeta) / element.Patch.NumberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID % (element.Patch.NumberOfControlPointsHeta * element.Patch.NumberOfControlPointsZeta) % element.Patch.NumberOfControlPointsZeta;
sumKsiHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsiHetaZeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsidHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsiHetadZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
}
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID / (element.Patch.NumberOfControlPointsHeta * element.Patch.NumberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID % (element.Patch.NumberOfControlPointsHeta * element.Patch.NumberOfControlPointsZeta) / element.Patch.NumberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID % (element.Patch.NumberOfControlPointsHeta * element.Patch.NumberOfControlPointsZeta) % element.Patch.NumberOfControlPointsZeta;
NurbsValues[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / sumKsiHetaZeta;
NurbsDerivativeValuesKsi[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHetaZeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHetaZeta) *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesHeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHetaZeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHetaZeta) *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
(bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] * sumKsiHetaZeta -
bsplinesZeta.BSPLineValues[indexZeta, k] * sumKsiHetadZeta) *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
}
}
}
}
}
/// <summary>
/// Defines 3D NURBS shape functions given per axis gauss points.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="NurbsElement3D"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
/// <param name="parametricGaussPointKsi">An <see cref="IVector"/> containing Gauss points of axis Ksi.</param>
/// <param name="parametricGaussPointHeta">An <see cref="IVector"/> containing Gauss points of axis Heta.</param>
/// <param name="parametricGaussPointZeta">An <see cref="IVector"/> containing Gauss points of axis Zeta.</param>
public Nurbs3D(Element element, IList <ControlPoint> controlPoints, Vector parametricGaussPointKsi,
Vector parametricGaussPointHeta, Vector parametricGaussPointZeta)
{
var parametricPointsCount = parametricGaussPointKsi.Length * parametricGaussPointHeta.Length *
parametricGaussPointZeta.Length;
BSPLines1D bsplinesKsi = new BSPLines1D(element.Patch.DegreeKsi, element.Patch.KnotValueVectorKsi,
parametricGaussPointKsi);
BSPLines1D bsplinesHeta = new BSPLines1D(element.Patch.DegreeHeta, element.Patch.KnotValueVectorHeta,
parametricGaussPointHeta);
BSPLines1D bsplinesZeta = new BSPLines1D(element.Patch.DegreeZeta, element.Patch.KnotValueVectorZeta,
parametricGaussPointZeta);
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
bsplinesZeta.calculateBSPLinesAndDerivatives();
int supportKsi = parametricGaussPointKsi.Length;
int supportHeta = parametricGaussPointHeta.Length;
int supportZeta = parametricGaussPointZeta.Length;
int numberOfElementControlPoints = (element.Patch.DegreeKsi + 1) * (element.Patch.DegreeHeta + 1) *
(element.Patch.DegreeZeta + 1);
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsDerivativeValuesZeta = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
for (int k = 0; k < supportZeta; k++)
{
double sumKsiHetaZeta = 0;
double sumdKsiHetaZeta = 0;
double sumKsidHetaZeta = 0;
double sumKsiHetadZeta = 0;
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID /
(element.Patch.NumberOfControlPointsHeta *
element.Patch.NumberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID %
(element.Patch.NumberOfControlPointsHeta *
element.Patch.NumberOfControlPointsZeta) /
element.Patch.NumberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID %
(element.Patch.NumberOfControlPointsHeta *
element.Patch.NumberOfControlPointsZeta) %
element.Patch.NumberOfControlPointsZeta;
sumKsiHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsiHetaZeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsidHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsiHetadZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
}
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID /
(element.Patch.NumberOfControlPointsHeta *
element.Patch.NumberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID %
(element.Patch.NumberOfControlPointsHeta *
element.Patch.NumberOfControlPointsZeta) /
element.Patch.NumberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID %
(element.Patch.NumberOfControlPointsHeta *
element.Patch.NumberOfControlPointsZeta) %
element.Patch.NumberOfControlPointsZeta;
NurbsValues[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / sumKsiHetaZeta;
NurbsDerivativeValuesKsi[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHetaZeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHetaZeta) *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesHeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHetaZeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHetaZeta) *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
(bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] * sumKsiHetaZeta -
bsplinesZeta.BSPLineValues[indexZeta, k] * sumKsiHetadZeta) *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
}
}
}
}
}
/// <summary>
/// Define 3D NURBS shape function for a collocation point.
/// </summary>
/// <param name="numberOfControlPointsKsi">Number of control points along parametric axis Ksi.</param>
/// <param name="numberOfControlPointsHeta">Number of control points along parametric axis Heta.</param>
/// <param name="numberOfControlPointsZeta">Number of control points along parametric axis Zeta.</param>
/// <param name="degreeKsi">Polynomial degree of the parametric axis Ksi.</param>
/// <param name="degreeHeta">Polynomial degree of the parametric axis Heta.</param>
/// <param name="degreeZeta">Polynomial degree of the parametric axis Zeta.</param>
/// <param name="knotValueVectorKsi">Knot value vector of the parametric axis Ksi.</param>
/// <param name="knotValueVectorHeta">Knot value vector of the parametric axis Heta.</param>
/// <param name="knotValueVectorZeta">Knot value vector of the parametric axis Zeta.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the <see cref="Model"/>.</param>
/// <param name="collocationPoint">A <see cref="NaturalPoin"/> for which the shape functions will be evaluated.</param>
public Nurbs3D(int numberOfControlPointsKsi, int numberOfControlPointsHeta, int numberOfControlPointsZeta,
int degreeKsi, int degreeHeta, int degreeZeta, Vector knotValueVectorKsi,
Vector knotValueVectorHeta, Vector knotValueVectorZeta, ControlPoint[] controlPoints,
NaturalPoint collocationPoint)
{
BSPLines1D bsplinesKsi =
new BSPLines1D(degreeKsi, knotValueVectorKsi, Vector.CreateFromArray(new double[] { collocationPoint.Xi }));
BSPLines1D bsplinesHeta = new BSPLines1D(degreeHeta, knotValueVectorHeta,
Vector.CreateFromArray(new double[] { collocationPoint.Eta }));
BSPLines1D bsplinesZeta = new BSPLines1D(degreeZeta, knotValueVectorZeta,
Vector.CreateFromArray(new double[] { collocationPoint.Zeta }));
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
bsplinesZeta.calculateBSPLinesAndDerivatives();
int supportKsi = degreeKsi + 1;
int supportHeta = degreeHeta + 1;
int supportZeta = degreeZeta + 1;
int numberOfGPKsi = 1;
int numberOfGPHeta = 1;
int numberOfGPZeta = 1;
int numberOfElementControlPoints = supportKsi * supportHeta * supportZeta;
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsDerivativeValuesZeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueKsi = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueHeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueZeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueKsiHeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueKsiZeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueHetaZeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
for (int i = 0; i < numberOfGPKsi; i++)
{
for (int j = 0; j < numberOfGPHeta; j++)
{
for (int k = 0; k < numberOfGPZeta; k++)
{
double sumKsiHetaZeta = 0;
double sumdKsiHetaZeta = 0;
double sumKsidHetaZeta = 0;
double sumKsiHetadZeta = 0;
double sumdKsidKsi = 0;
double sumdHetadHeta = 0;
double sumdZetadZeta = 0;
double sumdKsidHeta = 0;
double sumdKsidZeta = 0;
double sumdHetadZeta = 0;
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID /
(numberOfControlPointsHeta *
numberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) /
numberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) %
numberOfControlPointsZeta;
sumKsiHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsiHetaZeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsidHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsiHetadZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsidKsi += bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdHetadHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdZetadZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineSecondDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsidHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsidZeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdHetadZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
}
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID /
(numberOfControlPointsHeta *
numberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) /
numberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) %
numberOfControlPointsZeta;
NurbsValues[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / sumKsiHetaZeta;
NurbsDerivativeValuesKsi[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHetaZeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHetaZeta) *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesHeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHetaZeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHetaZeta) *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
(bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] * sumKsiHetaZeta -
bsplinesZeta.BSPLineValues[indexZeta, k] * sumKsiHetadZeta) *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsSecondDerivativeValueKsi[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] / sumKsiHetaZeta -
2 * bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumdKsiHetaZeta /
Math.Pow(sumKsiHetaZeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsidKsi / Math.Pow(sumKsiHetaZeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * Math.Pow(sumdKsiHetaZeta, 2) /
Math.Pow(sumKsiHetaZeta, 3)) *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
NurbsSecondDerivativeValueHeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
(bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] / sumKsiHetaZeta -
2 * bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsidHetaZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumdHetadHeta / Math.Pow(sumKsiHetaZeta, 2) +
2 * bsplinesHeta.BSPLineValues[indexHeta, j] * Math.Pow(sumKsidHetaZeta, 2) / Math.Pow(sumKsiHetaZeta, 3)) *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
NurbsSecondDerivativeValueZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
(bsplinesZeta.BSPLineSecondDerivativeValues[indexZeta, k] / sumKsiHetaZeta -
2 * bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] * sumKsiHetadZeta /
Math.Pow(sumKsiHetaZeta, 2) -
bsplinesZeta.BSPLineValues[indexZeta, k] * sumdZetadZeta /
Math.Pow(sumKsiHetaZeta, 2) +
2 * bsplinesZeta.BSPLineValues[indexZeta, k] * Math.Pow(sumKsiHetadZeta, 2) /
Math.Pow(sumKsiHetaZeta, 3)) *
controlPoints[m].WeightFactor;
NurbsSecondDerivativeValueKsiHeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] / sumKsiHetaZeta -
bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
sumKsidHetaZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
sumdKsiHetaZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsidHeta / Math.Pow(sumKsiHetaZeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsiHetaZeta * sumKsidHetaZeta / Math.Pow(sumKsiHetaZeta, 3)) *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
NurbsSecondDerivativeValueKsiZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] / sumKsiHetaZeta -
bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
sumKsiHetadZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
sumdKsiHetaZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesZeta.BSPLineValues[indexZeta, k] *
sumdKsidZeta / Math.Pow(sumKsiHetaZeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesZeta.BSPLineValues[indexZeta, k] *
sumdKsiHetaZeta * sumKsiHetadZeta / Math.Pow(sumKsiHetaZeta, 3)) *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[m].WeightFactor;
NurbsSecondDerivativeValueHetaZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] / sumKsiHetaZeta -
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
sumKsiHetadZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
sumKsidHetaZeta / Math.Pow(sumKsiHetaZeta, 2) -
bsplinesHeta.BSPLineValues[indexHeta, j] * bsplinesZeta.BSPLineValues[indexZeta, k] *
sumdHetadZeta / Math.Pow(sumKsiHetaZeta, 2) +
2 * bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
sumKsidHetaZeta * sumKsiHetadZeta / Math.Pow(sumKsiHetaZeta, 3)) *
controlPoints[m].WeightFactor;
}
}
}
}
}
/// <summary>
/// Define 3D NURBS shape function without needing an element definition.
/// </summary>
/// <param name="numberOfControlPointsKsi">Number of control points along parametric axis Ksi.</param>
/// <param name="numberOfControlPointsHeta">Number of control points along parametric axis Heta.</param>
/// <param name="numberOfControlPointsZeta">Number of control points along parametric axis Zeta.</param>
/// <param name="degreeKsi">Polynomial degree of the parametric axis Ksi.</param>
/// <param name="degreeHeta">Polynomial degree of the parametric axis Heta.</param>
/// <param name="degreeZeta">Polynomial degree of the parametric axis Zeta.</param>
/// <param name="knotValueVectorKsi">Knot value vector of the parametric axis Ksi.</param>
/// <param name="knotValueVectorHeta">Knot value vector of the parametric axis Heta.</param>
/// <param name="knotValueVectorZeta">Knot value vector of the parametric axis Zeta.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
/// <param name="gaussPoints">A <see cref="List{T}"/> containing the control points where the shape functions will be evaluated.</param>
public Nurbs3D(int numberOfControlPointsKsi, int numberOfControlPointsHeta, int numberOfControlPointsZeta,
int degreeKsi, int degreeHeta, int degreeZeta, Vector knotValueVectorKsi,
Vector knotValueVectorHeta, Vector knotValueVectorZeta, ControlPoint[] controlPoints,
GaussLegendrePoint3D[] gaussPoints)
{
var numberOfGaussPoints = gaussPoints.Length;
var parametricGaussPointKsi = Vector.CreateZero(degreeKsi + 1);
for (int i = 0; i < degreeKsi + 1; i++)
{
parametricGaussPointKsi[i] = gaussPoints[i * (degreeZeta + 1) * (degreeHeta + 1)].Ksi;
}
var parametricGaussPointHeta = Vector.CreateZero(degreeHeta + 1);
for (int i = 0; i < degreeHeta + 1; i++)
{
parametricGaussPointHeta[i] = gaussPoints[i * (degreeZeta + 1)].Heta;
}
var parametricGaussPointZeta = Vector.CreateZero(degreeZeta + 1);
for (int i = 0; i < degreeZeta + 1; i++)
{
parametricGaussPointZeta[i] = gaussPoints[i].Zeta;
}
BSPLines1D bsplinesKsi =
new BSPLines1D(degreeKsi, knotValueVectorKsi, parametricGaussPointKsi);
BSPLines1D bsplinesHeta = new BSPLines1D(degreeHeta, knotValueVectorHeta,
parametricGaussPointHeta);
BSPLines1D bsplinesZeta = new BSPLines1D(degreeZeta, knotValueVectorZeta,
parametricGaussPointZeta);
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
bsplinesZeta.calculateBSPLinesAndDerivatives();
int supportKsi = degreeKsi + 1;
int supportHeta = degreeHeta + 1;
int supportZeta = degreeZeta + 1;
int numberOfElementControlPoints = supportKsi * supportHeta * supportZeta;
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, numberOfGaussPoints);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, numberOfGaussPoints);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, numberOfGaussPoints);
NurbsDerivativeValuesZeta = Matrix.CreateZero(numberOfElementControlPoints, numberOfGaussPoints);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
for (int k = 0; k < supportZeta; k++)
{
double sumKsiHetaZeta = 0;
double sumdKsiHetaZeta = 0;
double sumKsidHetaZeta = 0;
double sumKsiHetadZeta = 0;
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID /
(numberOfControlPointsHeta *
numberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) /
numberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) %
numberOfControlPointsZeta;
sumKsiHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumdKsiHetaZeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsidHetaZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor;
sumKsiHetadZeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] *
controlPoints[m].WeightFactor;
}
for (int m = 0; m < numberOfElementControlPoints; m++)
{
int indexKsi = controlPoints[m].ID /
(numberOfControlPointsHeta *
numberOfControlPointsZeta);
int indexHeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) /
numberOfControlPointsZeta;
int indexZeta = controlPoints[m].ID %
(numberOfControlPointsHeta *
numberOfControlPointsZeta) %
numberOfControlPointsZeta;
NurbsValues[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / sumKsiHetaZeta;
NurbsDerivativeValuesKsi[m, i *supportHeta *supportZeta + j * supportZeta + k] =
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHetaZeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHetaZeta) *
bsplinesHeta.BSPLineValues[indexHeta, j] *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesHeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHetaZeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHetaZeta) *
bsplinesZeta.BSPLineValues[indexZeta, k] *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
NurbsDerivativeValuesZeta[m, i *supportHeta *supportZeta + j * supportZeta + k] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
(bsplinesZeta.BSPLineDerivativeValues[indexZeta, k] * sumKsiHetaZeta -
bsplinesZeta.BSPLineValues[indexZeta, k] * sumKsiHetadZeta) *
controlPoints[m].WeightFactor / Math.Pow(sumKsiHetaZeta, 2);
}
}
}
}
}
/// <summary>
/// Defines n 2D NURBS shape function for a face element.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="NurbsElement2D"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
/// <param name="face">The two-dimensional boundary entities where the <paramref name="element"/> shape functions will be evaluated.</param>
public Nurbs2D(Element element, ControlPoint[] controlPoints, Face face)
{
var degreeKsi = face.Degrees[0];
var degreeHeta = face.Degrees[1];
var knotValueVectorKsi = face.KnotValueVectors[0];
var knotValueVectorHeta = face.KnotValueVectors[1];
var numberOfControlPointsHeta = knotValueVectorHeta.Length - degreeHeta - 1;
GaussQuadrature gauss = new GaussQuadrature();
IList <GaussLegendrePoint3D> gaussPoints =
gauss.CalculateElementGaussPoints(degreeKsi, degreeHeta, element.Knots.ToArray());
var parametricGaussPointKsi = Vector.CreateZero(degreeKsi + 1);
for (int i = 0; i < degreeKsi + 1; i++)
{
parametricGaussPointKsi[i] = gaussPoints[i * (degreeHeta + 1)].Ksi;
}
var parametricGaussPointHeta = Vector.CreateZero(degreeHeta + 1);
for (int i = 0; i < degreeHeta + 1; i++)
{
parametricGaussPointHeta[i] = gaussPoints[i].Heta;
}
BSPLines1D bsplinesKsi = new BSPLines1D(degreeKsi, knotValueVectorKsi, parametricGaussPointKsi);
BSPLines1D bsplinesHeta = new BSPLines1D(degreeHeta, knotValueVectorHeta, parametricGaussPointHeta);
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
int supportKsi = degreeKsi + 1;
int supportHeta = degreeHeta + 1;
int numberOfElementControlPoints = supportKsi * supportHeta;
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsSecondDerivativeValueKsi = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsSecondDerivativeValueHeta = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
NurbsSecondDerivativeValueKsiHeta = Matrix.CreateZero(numberOfElementControlPoints, gaussPoints.Count);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
double sumKsiHeta = 0;
double sumdKsiHeta = 0;
double sumKsidHeta = 0;
double sumdKsidKsi = 0;
double sumdHetadHeta = 0;
double sumdKsidHeta = 0;
for (int k = 0; k < numberOfElementControlPoints; k++)
{
int indexKsi =
face.ControlPointsDictionary.First(cp => cp.Value.ID == controlPoints[k].ID).Key /
numberOfControlPointsHeta;
int indexHeta =
face.ControlPointsDictionary.First(cp => cp.Value.ID == controlPoints[k].ID).Key %
numberOfControlPointsHeta;
sumKsiHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsiHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumKsidHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsidKsi += bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdHetadHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsidHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
}
for (int k = 0; k < numberOfElementControlPoints; k++)
{
int indexKsi =
face.ControlPointsDictionary.First(cp => cp.Value.ID == controlPoints[k].ID).Key /
numberOfControlPointsHeta;
int indexHeta =
face.ControlPointsDictionary.First(cp => cp.Value.ID == controlPoints[k].ID).Key %
numberOfControlPointsHeta;
NurbsValues[k, i *supportHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor / sumKsiHeta;
NurbsDerivativeValuesKsi[k, i *supportHeta + j] =
bsplinesHeta.BSPLineValues[indexHeta, j] * controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHeta) / Math.Pow(sumKsiHeta, 2);
NurbsDerivativeValuesHeta[k, i *supportHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[k].WeightFactor *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHeta) / Math.Pow(sumKsiHeta, 2);
NurbsSecondDerivativeValueKsi[k, i *supportHeta + j] =
bsplinesHeta.BSPLineValues[indexHeta, j] * controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] / sumKsiHeta -
2 * bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsidKsi / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * Math.Pow(sumdKsiHeta, 2) /
Math.Pow(sumKsiHeta, 3));
NurbsSecondDerivativeValueHeta[k, i *supportHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[k].WeightFactor *
(bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] / sumKsiHeta -
2 * bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumdHetadHeta / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesHeta.BSPLineValues[indexHeta, j] * Math.Pow(sumKsidHeta, 2) /
Math.Pow(sumKsiHeta, 3));
NurbsSecondDerivativeValueKsiHeta[k, i *supportHeta + j] =
controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] / sumKsiHeta -
bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
sumKsidHeta / Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
sumdKsiHeta / Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsidHeta / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsiHeta * sumKsidHeta / Math.Pow(sumKsiHeta, 3));
}
}
}
}
/// <summary>
/// Defines a 2D NURBS shape function for an element given the per axis gauss point coordinates.
/// </summary>
/// <param name="element">An <see cref="Element"/> of type <see cref="NurbsElement2D"/>.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
/// <param name="parametricGaussPointKsi">An <see cref="IVector"/> containing Gauss points of axis Ksi.</param>
/// <param name="parametricGaussPointHeta">An <see cref="IVector"/> containing Gauss points of axis Heta.</param>
public Nurbs2D(Element element, ControlPoint[] controlPoints, IVector parametricGaussPointKsi,
IVector parametricGaussPointHeta)
{
var parametricPointsCount = parametricGaussPointKsi.Length * parametricGaussPointHeta.Length;
BSPLines1D bsplinesKsi = new BSPLines1D(element.Patch.DegreeKsi, element.Patch.KnotValueVectorKsi,
parametricGaussPointKsi);
BSPLines1D bsplinesHeta = new BSPLines1D(element.Patch.DegreeHeta, element.Patch.KnotValueVectorHeta,
parametricGaussPointHeta);
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
int supportKsi = parametricGaussPointKsi.Length;
int supportHeta = parametricGaussPointHeta.Length;
int numberOfElementControlPoints = (element.Patch.DegreeKsi + 1) * (element.Patch.DegreeHeta + 1);
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsSecondDerivativeValueKsi = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsSecondDerivativeValueHeta = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
NurbsSecondDerivativeValueKsiHeta = Matrix.CreateZero(numberOfElementControlPoints, parametricPointsCount);
for (int i = 0; i < supportKsi; i++)
{
for (int j = 0; j < supportHeta; j++)
{
double sumKsiHeta = 0;
double sumdKsiHeta = 0;
double sumKsidHeta = 0;
double sumdKsidKsi = 0;
double sumdHetadHeta = 0;
double sumdKsidHeta = 0;
for (int k = 0; k < numberOfElementControlPoints; k++)
{
int indexKsi = controlPoints[k].ID / element.Patch.NumberOfControlPointsHeta;
int indexHeta = controlPoints[k].ID % element.Patch.NumberOfControlPointsHeta;
sumKsiHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsiHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumKsidHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsidKsi += bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdHetadHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsidHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
}
for (int k = 0; k < numberOfElementControlPoints; k++)
{
int indexKsi = controlPoints[k].ID / element.Patch.NumberOfControlPointsHeta;
int indexHeta = controlPoints[k].ID % element.Patch.NumberOfControlPointsHeta;
NurbsValues[k, i *supportHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor / sumKsiHeta;
NurbsDerivativeValuesKsi[k, i *supportHeta + j] =
bsplinesHeta.BSPLineValues[indexHeta, j] * controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHeta) / Math.Pow(sumKsiHeta, 2);
NurbsDerivativeValuesHeta[k, i *supportHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[k].WeightFactor *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHeta) / Math.Pow(sumKsiHeta, 2);
NurbsSecondDerivativeValueKsi[k, i *supportHeta + j] =
bsplinesHeta.BSPLineValues[indexHeta, j] * controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] / sumKsiHeta -
2 * bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsidKsi / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * Math.Pow(sumdKsiHeta, 2) /
Math.Pow(sumKsiHeta, 3));
NurbsSecondDerivativeValueHeta[k, i *supportHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[k].WeightFactor *
(bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] / sumKsiHeta -
2 * bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumdHetadHeta / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesHeta.BSPLineValues[indexHeta, j] * Math.Pow(sumKsidHeta, 2) /
Math.Pow(sumKsiHeta, 3));
NurbsSecondDerivativeValueKsiHeta[k, i *supportHeta + j] =
controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] / sumKsiHeta -
bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
sumKsidHeta / Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
sumdKsiHeta / Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsidHeta / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsiHeta * sumKsidHeta / Math.Pow(sumKsiHeta, 3));
}
}
}
}
/// <summary>
/// Defines a 2D NURBS shape functions for a collocation point.
/// Calculates NURBS for only Control Points affected by the collocation point.
/// </summary>
/// <param name="degreeKsi">Polynomial degree of the parametric axis Ksi.</param>
/// <param name="degreeHeta">Polynomial degree of the parametric axis Heta.</param>
/// <param name="knotValueVectorKsi">Knot value vector of the parametric axis Ksi.</param>
/// <param name="knotValueVectorHeta">Knot value vector of the parametric axis Heta.</param>
/// <param name="collocationPoint">A <see cref="NaturalPoin"/> for which the shape functions will be evaluated.</param>
/// <param name="controlPoints">A <see cref="List{T}"/> containing the control points of the element.</param>
public Nurbs2D(int degreeKsi, int degreeHeta, Vector knotValueVectorKsi, Vector knotValueVectorHeta,
NaturalPoint collocationPoint, IList <ControlPoint> controlPoints)
{
var numberOfControlPointsHeta = knotValueVectorHeta.Length - degreeHeta - 1;
BSPLines1D bsplinesKsi = new BSPLines1D(degreeKsi, knotValueVectorKsi,
Vector.CreateFromArray(new double[] { collocationPoint.Xi }));
BSPLines1D bsplinesHeta = new BSPLines1D(degreeHeta, knotValueVectorHeta,
Vector.CreateFromArray(new double[] { collocationPoint.Eta }));
bsplinesKsi.calculateBSPLinesAndDerivatives();
bsplinesHeta.calculateBSPLinesAndDerivatives();
int numberOfGPKsi = 1;
int numberOfGPHeta = 1;
int numberOfElementControlPoints = (degreeKsi + 1) * (degreeHeta + 1);
NurbsValues = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsDerivativeValuesKsi = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsDerivativeValuesHeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueKsi = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueHeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
NurbsSecondDerivativeValueKsiHeta = Matrix.CreateZero(numberOfElementControlPoints, 1);
for (int i = 0; i < numberOfGPKsi; i++)
{
for (int j = 0; j < numberOfGPHeta; j++)
{
double sumKsiHeta = 0;
double sumdKsiHeta = 0;
double sumKsidHeta = 0;
double sumdKsidKsi = 0;
double sumdHetadHeta = 0;
double sumdKsidHeta = 0;
for (int k = 0; k < numberOfElementControlPoints; k++)
{
// Why type casting is needed.?
int indexKsi = controlPoints[k].ID / numberOfControlPointsHeta;
int indexHeta = controlPoints[k].ID % numberOfControlPointsHeta;
sumKsiHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsiHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumKsidHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsidKsi += bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdHetadHeta += bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
sumdKsidHeta += bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
controlPoints[k].WeightFactor;
}
for (int k = 0; k < numberOfElementControlPoints; k++)
{
int indexKsi = controlPoints[k].ID / numberOfControlPointsHeta;
int indexHeta = controlPoints[k].ID % numberOfControlPointsHeta;
NurbsValues[k, i *numberOfGPHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
controlPoints[k].WeightFactor / sumKsiHeta;
NurbsDerivativeValuesKsi[k, i *numberOfGPHeta + j] =
bsplinesHeta.BSPLineValues[indexHeta, j] * controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumKsiHeta -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsiHeta) / Math.Pow(sumKsiHeta, 2);
NurbsDerivativeValuesHeta[k, i *numberOfGPHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[k].WeightFactor *
(bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsiHeta -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumKsidHeta) / Math.Pow(sumKsiHeta, 2);
NurbsSecondDerivativeValueKsi[k, i *numberOfGPHeta + j] =
bsplinesHeta.BSPLineValues[indexHeta, j] * controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineSecondDerivativeValues[indexKsi, i] / sumKsiHeta -
2 * bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] * sumdKsiHeta /
Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * sumdKsidKsi / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * Math.Pow(sumdKsiHeta, 2) /
Math.Pow(sumKsiHeta, 3));
NurbsSecondDerivativeValueHeta[k, i *numberOfGPHeta + j] =
bsplinesKsi.BSPLineValues[indexKsi, i] * controlPoints[k].WeightFactor *
(bsplinesHeta.BSPLineSecondDerivativeValues[indexHeta, j] / sumKsiHeta -
2 * bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] * sumKsidHeta /
Math.Pow(sumKsiHeta, 2) -
bsplinesHeta.BSPLineValues[indexHeta, j] * sumdHetadHeta / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesHeta.BSPLineValues[indexHeta, j] * Math.Pow(sumKsidHeta, 2) /
Math.Pow(sumKsiHeta, 3));
NurbsSecondDerivativeValueKsiHeta[k, i *numberOfGPHeta + j] =
controlPoints[k].WeightFactor *
(bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] / sumKsiHeta -
bsplinesKsi.BSPLineDerivativeValues[indexKsi, i] *
bsplinesHeta.BSPLineValues[indexHeta, j] *
sumKsidHeta / Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] *
bsplinesHeta.BSPLineDerivativeValues[indexHeta, j] *
sumdKsiHeta / Math.Pow(sumKsiHeta, 2) -
bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsidHeta / Math.Pow(sumKsiHeta, 2) +
2 * bsplinesKsi.BSPLineValues[indexKsi, i] * bsplinesHeta.BSPLineValues[indexHeta, j] *
sumdKsiHeta * sumKsidHeta / Math.Pow(sumKsiHeta, 3));
}
}
}
}