function p = amdbar (S) % AMDBAR Symmetric approximate minimum degree permutation. % P = AMDBAR (S), for a symmetric positive definite matrix S, % returns the permutation vector p such that S(p,p) tends to have a % sparser Cholesky factor than S. Sometimes AMDBAR works well % for symmetric indefinite matrices too. AMDBAR tends to be much faster % than SYMMMD and tends to return a better ordering. WARNING: AMDBAR does % not drop dense rows and columns in A (they should be ordered last, prior % to calling AMDBAR, but this routine does not do that). A single dense row % can cause AMDBAR to take time proportional to n^2 to compute the ordering. % If you have dense rows/columns, use SYMAMD or SYMMMD instead, or drop them % from your matrix prior to calling this routine. % % See also SYMAMDTREE, COLAMD, COLAMDTREE, COLMMD, SYMMMD, SYMRCM, COLPERM. % % Authors: % Amdbar was written by Timothy A. Davis, Patrick Amestoy, Iain S. Duff, % and John K. Reid. Timothy A. Davis (davis@cise.ufl.edu), University % of Florida, wrote the Matlab interface for amdbar. % % ************************************************************************ % * NOTICE: "The AMD routines (AMDEXA, AMDBAR, AMDHAF, AMDHAT, AMDTRU, % * and AMDATR) may be used SOLELY for educational, research, and % * benchmarking purposes by non-profit organizations and the U.S. % * government. Commercial and other organizations may make use of the % * AMD routines SOLELY for benchmarking purposes only. The AMD % * routines may be modified by or on behalf of the User for such % * use but at no time shall the AMD routines or any such modified % * version of them become the property of the User. The AMD routines % * are provided without warranty of any kind, either expressed or % * implied. Neither the Authors nor their employers shall be liable % * for any direct or consequential loss or damage whatsoever arising % * out of the use or misuse of the AMD routines by the User. The AMD % * routines must not be sold. You may make copies of the AMD routines, % * but this NOTICE and the Copyright notice must appear in all copies. % * Any other use of the AMD routines requires written permission. % * Your use of the AMD routines is an implicit agreement to these % * conditions." % ************************************************************************ % % This work was supported by the National Science Foundation, under grants % DMS-9504974 and DMS-9803599. AMDBAR is available at % http://www.cise.ufl.edu/~davis/amd, and http://www.netlib.org/linalg/amd. % Tested under Matlab 5.2.0.3084, using Solaris 2.6. August 6, 1998. % This file is provided so that "help amdbar" prints the above description. help amdbar disp ('Warning! Valid amdbar mexFunction not found. Using symmmd instead.') ; p = symmmd (S) ; .