close

Close Audio Video Interleaved (AVI) file

Syntax

*

aviobj = close(aviobj)

Description

aviobj = close(aviobj) finishes writing and closes the AVI file associated with aviobj, which is an AVI file object, created using the avifile function.


closereq

Default figure close request function

Syntax

*

closereq

Description

closereq delete the current figure.


cmopts

Get name of source control system

Graphical Interface

As an alternative to cmopts, use preferences. Select File -> Preferences in the MATLAB desktop, and then select General -> Source Control.

Syntax

*

cmopts

Description

cmopts returns the name of the source control system you selected using preferences, which is one of the following:

*

clearcase
customverctrl
pvcs
rcs
sourcesafe

If you have not selected a source control system, cmopts returns

*

none

Specifying a Source Control System

To specify the source control system:

1. From the MATLAB Editor window or from a Simulink or Stateflow model window, select File -> Preferences.

The Preferences dialog box opens.

2. In the left pane, click the + for General, and then select Source Control.

The currently selected system is shown.

3. Select the system you want to use from the Source control system list.
4. Click OK.

For more information, see source control preferences.

Examples

Type cmopts and MATLAB returns rcs, meaning the source control system specified in preferences is RCS.



colamd

Column approximate minimum degree permutation

Syntax

*

p = colamd(S)
p = colamd(S,knobs)
[p,stats] = colamd(S)
[p,stats] = colamd(S,knobs)

Description

p = colamd(S) returns the column approximate minimum degree permutation vector for the sparse matrix S. For a non-symmetric matrix S, S(:,p) tends to have sparser LU factors than S. The Cholesky factorization of S(:,p)' * S(:,p) also tends to be sparser than that of S'*S.

knobs is a two-element vector. If S is m-by-n, then rows with more than (knobs(1))*n entries are ignored. Columns with more than (knobs(2))*m entries are removed prior to ordering, and ordered last in the output permutation p. If the knobs parameter is not present, then knobs(1) = knobs(2) = spparms('wh_frac').

stats is an optional vector that provides data about the ordering and the validity of the matrix S.

stats(1)
Number of dense or empty rows ignored by colamd
stats(2)
Number of dense or empty columns ignored by colamd
stats(3)
Number of garbage collections performed on the internal data structure used by colamd (roughly of size 2.2*nnz(S) + 4*m + 7*n integers)
stats(4)
0 if the matrix is valid, or 1 if invalid
stats(5)
Rightmost column index that is unsorted or contains duplicate entries, or 0 if no such column exists
stats(6)
Last seen duplicate or out-of-order row index in the column index given by stats(5), or 0 if no such row index exists
stats(7)
Number of duplicate and out-of-order row indices

Although, MATLAB built-in functions generate valid sparse matrices, a user may construct an invalid sparse matrix using the MATLAB C or Fortran APIs and pass it to colamd. For this reason, colamd verifies that S is valid:

* If a row index appears two or more times in the same column, colamd ignores the duplicate entries, continues processing, and provides information about the duplicate entries in stats(4:7).
* If row indices in a column are out of order, colamd sorts each column of its internal copy of the matrix S (but does not repair the input matrix S), continues processing, and provides information about the out-of-order entries in stats(4:7).
* If S is invalid in any other way, colamd cannot continue. It prints an error message, and returns no output arguments (p or stats) .

The ordering is followed by a column elimination tree post-ordering.

Note colamd tends to be faster than colmmd and tends to return a better ordering.



colmmd

Sparse column minimum degree permutation

Syntax

*

p = colmmd(S)

Description

p = colmmd(S) returns the column minimum degree permutation vector for the sparse matrix S. For a nonsymmetric matrix S, this is a column permutation p such that S(:,p) tends to have sparser LU factors than S.

The colmmd permutation is automatically used by \ and / for the solution of nonsymmetric and symmetric indefinite sparse linear systems.

Use spparms to change some options and parameters associated with heuristics in the algorithm.

Algorithm

The minimum degree algorithm for symmetric matrices is described in the review paper by George and Liu [1]. For nonsymmetric matrices, the MATLAB minimum degree algorithm is new and is described in the paper by Gilbert, Moler, and Schreiber [2]. It is roughly like symmetric minimum degree for A'*A, but does not actually form A'*A.

Each stage of the algorithm chooses a vertex in the graph of A'*A of lowest degree (that is, a column of A having nonzero elements in common with the fewest other columns), eliminates that vertex, and updates the remainder of the graph by adding fill (that is, merging rows). If the input matrix S is of size m-by-n, the columns are all eliminated and the permutation is complete after n stages. To speed up the process, several heuristics are used to carry out multiple stages simultaneously.