biharmonic13PointsStencil

 The 13-points Biharmonic stencil for arbitrary step sizes in X/Y
 
 Input:
   hx: grid step size in X (defaults to 1 if not set)
   hy: grid step size in Y (defaults to hx if not set)
 
 Output:
   stencil: the 5x5 13-points Biharmonic (a.k.a. BiLaplacian) stencil

0001 function stencil = biharmonic13PointsStencil(hx, hy)
0002 % The 13-points Biharmonic stencil for arbitrary step sizes in X/Y
0003 %
0004 % Input:
0005 %   hx: grid step size in X (defaults to 1 if not set)
0006 %   hy: grid step size in Y (defaults to hx if not set)
0007 %
0008 % Output:
0009 %   stencil: the 5x5 13-points Biharmonic (a.k.a. BiLaplacian) stencil
0010 %
0011 
0012 laplacianStencil = laplacian5PointsStencil(hx, hy);
0013 
0014 stencil = conv2(laplacianStencil, laplacianStencil);
0015 
0016 end