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Operators and Keywords

Function List:

C++ API

: [count, h, parent, post, R] = symbfact (S)
: […] = symbfact (S, typ)
: […] = symbfact (S, typ, mode)

Perform a symbolic factorization analysis of the sparse matrix S.

The input variables are

S

S is a real or complex sparse matrix.

typ

Is the type of the factorization and can be one of

"sym" (default)

Factorize S. Assumes S is symmetric and uses the upper triangular portion of the matrix.

"col"

Factorize S' * S.

"row"

Factorize S * S'.

"lo"

Factorize S'. Assumes S is symmetric and uses the lower triangular portion of the matrix.

mode

When mode is unspecified return the Cholesky factorization for R. If mode is "lower" or "L" then return the conjugate transpose R' which is a lower triangular factor. The conjugate transpose version is faster and uses less memory, but still returns the same values for all other outputs: count, h, parent, and post.

The output variables are:

count

The row counts of the Cholesky factorization as determined by typ. The computational difficulty of performing the true factorization using chol is sum (count .^ 2).

h

The height of the elimination tree.

parent

The elimination tree itself.

post

A sparse boolean matrix whose structure is that of the Cholesky factorization as determined by typ.

See also: chol, etree, treelayout.

Package: octave