private static int getWidth(DerivativeType type)
{
switch (type)
{
case DerivativeType.x:
//return 5;
return(3);
case DerivativeType.y:
return(1);
case DerivativeType.xy:
return(3);
}
return(-1); // It should never come to this!
}
private static int getHeight(DerivativeType type)
{
switch (type)
{
case DerivativeType.x:
return 1;
case DerivativeType.y:
//return 5;
return 3;
case DerivativeType.xy:
return 3;
}
return -1; // It should never come to this!
}
private static float[,] constructWeights(DerivativeType type)
{
switch (type)
{
case DerivativeType.x:
//return new float[5, 1] { { 1f / 12f }, { -8f / 12f }, { 0f }, { 8f / 12f }, { -1f / 12f } };
return new float[3, 1] { { 1f },{ 0f },{ -1f } };
case DerivativeType.y:
//return new float[1, 5] { { 1f / 12f, -8f / 12f, 0f, 8f / 12f, -1f / 12f } };
return new float[1, 3] { { 1f, 0f, -1f } };
case DerivativeType.xy:
return new float[3, 3] { { 1f / 4f, 0f, -1f / 4f }, { 0f, 0f, 0f }, { -1f / 4f, 0f, 1f / 4f } };
}
return null; // It should never come to this!
}
private static float[,] constructWeights(DerivativeType type)
{
switch (type)
{
case DerivativeType.x:
//return new float[5, 1] { { 1f / 12f }, { -8f / 12f }, { 0f }, { 8f / 12f }, { -1f / 12f } };
return(new float[3, 1] {
{ 1f }, { 0f }, { -1f }
});
case DerivativeType.y:
//return new float[1, 5] { { 1f / 12f, -8f / 12f, 0f, 8f / 12f, -1f / 12f } };
return(new float[1, 3] {
{ 1f, 0f, -1f }
});
case DerivativeType.xy:
return(new float[3, 3] {
{ 1f / 4f, 0f, -1f / 4f }, { 0f, 0f, 0f }, { -1f / 4f, 0f, 1f / 4f }
});
}
return(null); // It should never come to this!
}
protected void AllocValues(uint pointCnt)
{
if (Type == FieldValueType.ZScalar ||
Type == FieldValueType.ZVector2 ||
Type == FieldValueType.ZVector3)
{
// complex
if (DerivativeType.HasFlag(FieldDerivativeType.Value))
{
ComplexValues = new System.Numerics.Complex[pointCnt * Dof];
}
if (DerivativeType.HasFlag(FieldDerivativeType.Velocity))
{
ComplexVelocityValues = new System.Numerics.Complex[pointCnt * Dof];
}
if (DerivativeType.HasFlag(FieldDerivativeType.Acceleration))
{
ComplexAccelerationValues = new System.Numerics.Complex[pointCnt * Dof];
}
}
else
{
// double
if (DerivativeType.HasFlag(FieldDerivativeType.Value))
{
DoubleValues = new double[pointCnt * Dof];
}
if (DerivativeType.HasFlag(FieldDerivativeType.Velocity))
{
DoubleVelocityValues = new double[pointCnt * Dof];
}
if (DerivativeType.HasFlag(FieldDerivativeType.Acceleration))
{
DoubleAccelerationValues = new double[pointCnt * Dof];
}
}
}
public DerivativeKernel(IApplicableFilter decoratingFilter, DerivativeType type)
: base(decoratingFilter, DerivativeKernel.getWidth(type), DerivativeKernel.getHeight(type), constructWeights(type))
{
this.type = type;
}
public DerivativeKernel(IApplicableFilter decoratingFilter, DerivativeType type)
: base(decoratingFilter, DerivativeKernel.getWidth(type), DerivativeKernel.getHeight(type), constructWeights(type))
{
this.type = type;
}
public double CalculateDerivative(Func <double, double, double> function, double x, double y, DerivativeType type)
{
var xStep = 0.0;
var yStep = 0.0;
if (type == DerivativeType.X)
{
xStep = Epsilon;
}
else
{
yStep = Epsilon;
}
var derivative = (function(x + xStep, y + yStep) - function(x - xStep, y - yStep)) / (2 * (xStep + yStep));
return(derivative);
}