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etree

Elimination tree

Syntax

p = etree(A)
p = etree(A,'col')
p = etree(A,'sym')
[p,q] = etree(...)

Description

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 = etree(A,'sym') is the same as p = etree(A).

[p,q] = etree(...) also returns a postorder permutation q of the tree.

Introduced before R2006a