interpolD2D

 Returns a two-dimensional interpolator of 2nd-order
                m : Number of cells along x-axis
                n : Number of cells along y-axis
               c1 : Left interpolation coeff.
               c2 : Bottom interpolation coeff.
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 SPDX-License-Identifier: GPL-3.0-or-later
 © 2008-2024 San Diego State University Research Foundation (SDSURF).
 See LICENSE file or https://www.gnu.org/licenses/gpl-3.0.html for details.
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0001 function I = interpolD2D(m, n, c1, c2)
0002 % Returns a two-dimensional interpolator of 2nd-order
0003 %                m : Number of cells along x-axis
0004 %                n : Number of cells along y-axis
0005 %               c1 : Left interpolation coeff.
0006 %               c2 : Bottom interpolation coeff.
0007 % ----------------------------------------------------------------------------
0008 % SPDX-License-Identifier: GPL-3.0-or-later
0009 % © 2008-2024 San Diego State University Research Foundation (SDSURF).
0010 % See LICENSE file or https://www.gnu.org/licenses/gpl-3.0.html for details.
0011 % ----------------------------------------------------------------------------
0012 
0013     Ix = interpolD(m, c1);
0014     Iy = interpolD(n, c2);
0015     
0016     Im = sparse(m + 2, m);
0017     In = sparse(n + 2, n);
0018     
0019     Im(2:(m+2)-1, :) = speye(m, m);
0020     In(2:(n+2)-1, :) = speye(n, n);
0021     
0022     Sx = kron(In, Ix);
0023     Sy = kron(Iy, Im);
0024     
0025     I = [Sx Sy];
0026 end