symbfact

Purpose

Symbolic analysis of sparse Cholesky and LU factorization.

Synopsis

count = symbfact(A)
count = symbfact(A,'f')
[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. This function is much faster than chol(A).

count = symbfact(A,'f') lets you specify an option, where f can be

  • col to analyze A'*A (without forming it explicitly).
  • sym to obtain the same result as symbfact(A).
    [count,h,parent,post,R] = symbfact(...) also returns

  • the height of the elimination tree, h
  • the elimination tree itself, parent
  • a postordering permutation of the elimination tree, post
  • a 0-1 matrix R whose structure is that of chol(A)

    See Also

    chol, etree

    (c) Copyright 1994 by The MathWorks, Inc.