/// <summary>
/// Evaluates all polynomials in reference space
/// in this basis (see <see cref="Polynomials"/>);
/// </summary>
/// <param name="Ns"></param>
/// <returns>
/// <list type="bullet">
/// <item>1st index: node index</item>
/// <item>2nd index: polynomial index</item>
/// </list>
/// </returns>
public virtual MultidimensionalArray Evaluate(NodeSet Ns)
{
int iKref = Ns.GetVolumeRefElementIndex(this.GridDat);
int N = this.Polynomials[iKref].Count;
MultidimensionalArray Values = this.GridDat.ChefBasis.BasisValues.GetValues(Ns, this.Degree);
if (Values.GetLength(1) == N)
{
return(Values);
}
else
{
return(Values.ExtractSubArrayShallow(new int[] { 0, 0 }, new int[] { Ns.NoOfNodes - 1, N - 1 }));
}
}
/// <summary>
/// A vectorized evaluation for the 2nd derivative, i.e. the Hessian, in physical coordinates: \f$ \partial^2_{\vec{x}} \phi_{j n} \f$.
/// </summary>
/// <param name="Nodes"></param>
/// <param name="j0">Index of first cell in the vector</param>
/// <param name="Len">Length of the vector</param>
/// <returns>
/// - 1st index: cell
/// - 2nd index: node index <em>m</em>
/// - 3rd index: polynomial index <em>n</em>
/// - 4th index: spatial direction of 1st derivation, <em>k</em>
/// - 5th index: spatial direction of 2nd derivation, <em>l</em>
/// So, the entry [m,n,k,l] =
/// \f$
/// \frac{\partial}{\partial x_k} \frac{\partial}{\partial x_l} \phi_n (\vec{x}_m)
/// \f$, where \f$ \vec{x}_m \f$ is the
/// <em>m</em>-th vector in the nodeset #<paramref name="Nodes"/>.
/// </returns>
public MultidimensionalArray CellEval2ndDeriv(NodeSet Nodes, int j0, int Len)
{
int iKref = Nodes.GetVolumeRefElementIndex(this.GridDat);
int N = this.Polynomials[iKref].Count;
int D = this.GridDat.SpatialDimension;
MultidimensionalArray Values = this.GridDat.ChefBasis.CellBasisHessianValues.GetValue_Cell(Nodes, j0, Len, this.Degree);
if (Values.GetLength(2) == N)
{
return(Values);
}
else
{
return(Values.ExtractSubArrayShallow(new int[] { 0, 0, 0, 0, 0 }, new int[] { Len - 1, Nodes.NoOfNodes - 1, N - 1, D - 1, D - 1 }));
}
}
