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fvn_sparse/UMFPACK/MATLAB/umfpack2.m 2.2 KB
422234dc3   daniau   git-svn-id: https...
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  function [out1, out2, out3, out4, out5] = umfpack2(in1, in2, in3, in4, in5) %#ok
  %UMFPACK2 computes x=A\b, x=A/b, or lu (A) for a sparse matrix A
  % It is also a built-in function in MATLAB, used in x=A\b.
  %
  % Example:
  %
  % UMFPACK:                            |  MATLAB approximate equivalent:
  % ---------------------------------------------------------------------
  % x = umfpack2 (A, '\', b) ;          |  x = A \ b
  %                                     |
  % x = umfpack2 (b, '/', A) ;          |  x = b / A
  %                                     |
  % [L,U,P,Q] = umfpack2 (A) ;          |  [m,n] = size (A) ;
  %                                     |  I = speye (n) ;
  %                                     |  Q = I (:, colamd (A)) ;
  %                                     |  [L,U,P] = lu (A*Q) ;
  %                                     |
  % [L,U,P,Q,R] = umfpack2 (A) ;        |  [m,n] = size (A) ;
  %                                     |  I = speye (n) ;
  %                                     |  Q = I (:, colamd (A)) ;
  %                                     |  r = full (sum (abs (A), 2)) ;
  %                                     |  r (find (r == 0)) = 1 ;
  %                                     |  R = spdiags (r, 0, m, m) ;
  %                                     |  [L,U,P] = lu ((R\A)*Q) ;
  %                                     |
  % [P,Q,F,C] = umfpack2 (A, 'symbolic')|  [m,n] = size (A) ;
  %                                     |  I = speye (n) ;
  %                                     |  Q = I (:, colamd (A)) ;
  %                                     |  [count,h,parent,post] = ...
  %                                     |  symbfact (A*Q, 'col') ;
  %
  % A must be sparse.  It can be complex, singular, and/or rectangular.  A must be
  % square for '/' or '\'.  b must be a full real or complex vector.  For
  % [L,U,P,Q,R] = umfpack2 (A), the factorization is L*U = P*(R\A)*Q.  If A has a
  % mostly symmetric nonzero pattern, then replace "colamd" with "amd" in the
  % MATLAB-equivalent column in the table above.  Type umfpack_details for more
  % information.
  %
  % See also: lu_normest, colamd, amd, umfpack.
  % To use UMFPACK for an arbitrary b, see umfpack_solve.
  
  % Copyright 1995-2007 by Timothy A. Davis.
  
  help umfpack2
  error ('umfpack2 mexFunction not found') ;