p = etree(A)p = etree(A,'col')[p,q] = etree(...)
p = etree(A) returns an elimination tree for the square symmetric matrix whose upper triangle is that of A. p(j) is the parent of column j in the tree, or 0 if j is a root.
p = etree(A,'col') returns the elimination tree of A'*A.
[p,q] = etree(...) returns a postorder permutation q on the tree.
etreeplot(sprandsym(50, 0.1))
(c) Copyright 1994 by The MathWorks, Inc.