function value = adj_perm_bandwidth ( node_num, adj_num, adj_row, adj, ... perm, perm_inv ) %*****************************************************************************80 % %% ADJ_PERM_BANDWIDTH computes the bandwidth of a permuted adjacency matrix. % % Discussion: % % The matrix is defined by the adjacency information and a permutation. % % The routine also computes the bandwidth and the size of the envelope. % % Licensing: % % This code is distributed under the GNU LGPL license. % % Modified: % % 02 January 2007 % % Author: % % John Burkardt % % Reference: % % Alan George, Joseph Liu, % Computer Solution of Large Sparse Positive Definite Systems, % Prentice Hall, 1981. % % Parameters: % % Input, integer NODE_NUM, the number of nodes. % % Input, integer ADJ_NUM, the number of adjacency entries. % % Input, integer ADJ_ROW(NODE_NUM+1). Information about row I is stored % in entries ADJ_ROW(I) through ADJ_ROW(I+1)-1 of ADJ. % % Input, integer ADJ(ADJ_NUM), the adjacency structure. % For each row, it contains the column indices of the nonzero entries. % % Input, integer PERM(NODE_NUM), integer PERM_INV(NODE_NUM), the permutation % and inverse permutation. % % Output, integer ADJ_PERM_BANDWIDTH, the bandwidth of the permuted % adjacency matrix. % band_lo = 0; band_hi = 0; for i = 1 : node_num for j = adj_row(perm(i)) : adj_row(perm(i)+1)-1 col = perm_inv(adj(j)); band_lo = max ( band_lo, i - col ); band_hi = max ( band_hi, col - i ); end end value = band_lo + 1 + band_hi; return end