/// <summary>
/// Compare the value to the defined invalid value.
/// </summary>
/// <param name="gridPosition"></param>
/// <returns></returns>
public bool IsValid(Index gridPosition)
{
return(InvalidValue == null || Sample(gridPosition) != InvalidValue);
}
/// <summary>
/// Get the derivative at a data point. Not checking for InvalidValue.
/// </summary>
/// <param name="pos"></param>
/// <returns></returns>
public SquareMatrix SampleDerivative(Index pos)
{
//Debug.Assert(NumVectorDimensions == Size.Length);
int size = Math.Max(Size.Length, NumVectorDimensions);
SquareMatrix jacobian = new SquareMatrix(size);
// For all dimensions, so please reset each time.
Index samplePos = new Index(pos);
for (int dim = 0; dim < Size.Length; ++dim)
{
// Just to be sure, check thst no value was overwritten.
int posCpy = samplePos[dim];
// See whether a step to the right/left is possible.
samplePos[dim]++;
bool rightValid = (samplePos[dim] < Size[dim]) && Scalars[0].Sample(samplePos) != InvalidValue;
samplePos[dim] -= 2;
bool leftValid = (samplePos[dim] >= 0) && Scalars[0].Sample(samplePos) != InvalidValue;
samplePos[dim]++;
if (rightValid)
{
if (leftValid)
{
// Regular case. Interpolate.
samplePos[dim]++;
jacobian[dim] = Sample(samplePos).ToVec(size);
samplePos[dim] -= 2;
jacobian[dim] -= Sample(samplePos).ToVec(size);
jacobian[dim] *= 0.5f;
samplePos[dim]++;
}
else
{
// Left border.
samplePos[dim]++;
jacobian[dim] = Sample(samplePos).ToVec(size);
samplePos[dim]--;
jacobian[dim] -= Sample(samplePos).ToVec(size);
}
}
else
{
if (leftValid)
{
// Right border.
jacobian[dim] = Sample(samplePos).ToVec(size);
samplePos[dim]--;
jacobian[dim] -= Sample(samplePos).ToVec(size);
samplePos[dim]++;
}
else
{
// Weird case.
jacobian[dim] = new Vector(0, size);
}
}
Debug.Assert(posCpy == samplePos[dim]);
}
return(jacobian);
}
/// <summary> /// Returns a value from the grid. /// </summary> /// <param name="gridPosition"></param> /// <returns></returns> public abstract float Sample(Index gridPosition);