symbfact (MATLAB Functions)

Symbolic factorization analysis

Syntax

count = symbfact(A)
count = symbfact(A,'col')
count = symbfact(A,'sym')
[count,h,parent,post,R] = symbfact(...)

Description

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. symbfact 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 count = symbfact(A).

[count,h,parent,post,R] = symbfact(...) has several optional return values.

h
Height of the elimination tree

parent
The elimination tree itself

post
Postordering permutation of the elimination tree

R
0-1 matrix whose structure is that of chol(A)

`h`	Height of the elimination tree
`parent`	The elimination tree itself
`post`	Postordering permutation of the elimination tree
`R`	0-1 matrix whose structure is that of `chol`(`A`)

See Also

chol, etree, treelayout

symamd symmlq