function [count,h,parent,post,R] = symbfact(A,f)
%SYMBFACT Symbolic factorization analysis.
%   count = SYMBFACT(A) returns the vector of row counts for the upper
%   triangular Cholesky factor of a symmetric matrix whose upper triangle 
%   is that of A, assuming no cancellation during the factorization.  
%   This routine should be much faster than chol(A).
%
%   count = SYMBFACT(A,'col') analyzes A'*A (without forming it explicitly).
%   count = SYMBFACT(A,'sym') is the same as p = symbfact(A).
%
%   There are several optional return values:
%
%   [count,h,parent,post,R] = symbfact(...) also returns
%        the height of the elimination tree,
%        the elimination tree itself,
%        a postordering permutation of the elimination tree,
%        and a 0-1 matrix R whose structure is that of chol(A).
%
%   See also CHOL, ETREE, TREELAYOUT.

%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   $Revision: 5.4 $  $Date: 1997/11/21 23:44:54 $

if nargin <= 1,
    op = 'symanalyze';
elseif f(1) == 's' | f(1) == 'S',
    op = 'symanalyze';
elseif f(1) == 'c' | f(1) == 'C',
    op = 'colanalyze';
else 
    error ('Second argument must be ''sym'' or ''col''');
end

if     nargout <= 1
  count = sparsfun(op,A);
elseif nargout == 2
  [count,h] = sparsfun(op,A);
elseif nargout == 3
  [count,h,parent] = sparsfun(op,A);
elseif nargout == 4
  [count,h,parent,post] = sparsfun(op,A);
elseif nargout == 5
  [count,h,parent,post,R] = sparsfun(op,A);
end
