function psfPrecMatData = constructMatrix( PSFs, center, boundary, b, tol )%%       psfPrecMatData = constructMatrix( PSFs, center, boundary, b, tol );%%  Given (several) PSFs, the locations of the corresponding point sources, %  and the boudary condition, this function sets up the data (eigenvalues)%  needed for a circulant preconditioner defined by the PSFs.%%  Input:%         PSF  -  cell array containing the PSFs%      center  -  cell array with {i,j} entry containing%                 [row_index, col_index] of point source location for%                 PSF{i,j}%    boundary  -  character string indicating which boundary condition%                 is to be implemented%           b  -  blurred image%%  Optional Input:%         tol  -  tolerance used to "regularize" the preconditioner%                 (e.g., using Hanke, Nagy, Plemmons approach) %%  Output:%   psfPrecMatData -  cell array containing the data needed for the%                     preconditioner solve routines%%  J. Nagy  12/31/01if nargin == 4  tol = [];endswitch boundarycase 'zero'  psfPrecMatData = zeroPrecMatrix( PSFs, center, b, tol );case 'periodic'  psfPrecMatData = periodicPrecMatrix( PSFs, center, b, tol );case 'neumann'  psfPrecMatData = neumannPrecMatrix( PSFs, center, b, tol );otherwise  error('Incorrect boundary condition')end