num::laplacian_stencil_2d_4th

Defined in header <pde/stencil.hpp>

template <typename T>
void laplacian_stencil_2d_4th(const vec<T> &x, vec<T> &y, int N);  // (1)

void laplacian_stencil_2d_4th(const scalar_field_2d &x, scalar_field_2d &y);  // (2)

Fourth-order 2D Laplacian cross stencil.

\[ y_{ij} = \frac{1}{12}\bigl( -x_{i-2,j} + 16x_{i-1,j} - 30x_{i,j} + 16x_{i+1,j} - x_{i+2,j} -x_{i,j-2} + 16x_{i,j-1} + 16x_{i,j+1} - x_{i,j+2} \bigr) \]