Except for simple one-shot programs, it is not practical to have to define all the functions you need each time you need them. Instead, you will normally want to save them in a file so that you can easily edit them, and save them for use at a later time.
Octave does not require you to load function definitions from files before using them. You simply need to put the function definitions in a place where Octave can find them.
When Octave encounters an identifier that is undefined, it first looks for variables or functions that are already compiled and currently listed in its symbol table. If it fails to find a definition there, it searches a list of directories (the path) for files ending in .m that have the same base name as the undefined identifier.5 Once Octave finds a file with a name that matches, the contents of the file are read. If it defines a single function, it is compiled and executed. See Script Files, for more information about how you can define more than one function in a single file.
When Octave defines a function from a function file, it saves the full name of the file it read and the time stamp on the file. If the time stamp on the file changes, Octave may reload the file. When Octave is running interactively, time stamp checking normally happens at most once each time Octave prints the prompt. Searching for new function definitions also occurs if the current working directory changes.
Checking the time stamp allows you to edit the definition of a function while Octave is running, and automatically use the new function definition without having to restart your Octave session.
To avoid degrading performance unnecessarily by checking the time stamps on functions that are not likely to change, Octave assumes that function files in the directory tree octave-home/share/octave/version/m will not change, so it doesn’t have to check their time stamps every time the functions defined in those files are used. This is normally a very good assumption and provides a significant improvement in performance for the function files that are distributed with Octave.
If you know that your own function files will not change while you are
running Octave, you can improve performance by calling
ignore_function_time_stamp ("all"), so that Octave will
ignore the time stamps for all function files. Passing
"system" to this function resets the default behavior.
Edit the named function, or change editor settings.
edit is called with the name of a file or function as its
argument it will be opened in the text editor defined by
HOME(see below) and then edited. If no file is found, then the m-file variant, ending with
".m", will be considered. If still no file is found, then variants with a leading
"@"and then with both a leading
".m"will be considered.
HOMEto contain that function along with its current definition.
name.ccis specified, then it will search for
name.ccin the path and try to modify it, otherwise it will create a new .cc file in the current directory. If name happens to be an m-file or interpreter defined function, then the text of that function will be inserted into the .cc file as a comment.
Warning: You may need to clear name before the new definition
is available. If you are editing a .cc file, you will need to execute
mkoctfile name.cc before the definition will be
edit is called with field and value variables, the
value of the control field field will be set to value. If an
output argument is requested and the first input argument is
edit will return the value of the control field field.
If the control field does not exist, edit will return a structure
containing all fields and values. Thus,
edit get all returns a
complete control structure.
The following control fields are used:
This is the location of user local m-files. Be sure it is in your path. The default is ~/octave.
This is the name to put after the "## Author:" field of new functions. By
default it guesses from the
gecos field of the password database.
This is the e-mail address to list after the name in the author field. By
default it guesses
<$LOGNAME@$HOSTNAME>, and if
is not defined it uses
uname -n. You probably want to override
this. Be sure to use the format
GNU General Public License (default).
BSD-style license without advertising clause.
Your own default copyright and license.
Unless you specify ‘pd’, edit will prepend the copyright statement with "Copyright (C) yyyy Function Author".
This value determines whether the editor should be started in async mode
(editor is started in the background and Octave continues) or sync mode
(Octave waits until the editor exits). Set it to
"sync" to start
the editor in sync mode. The default is
Determines whether files should be edited in place, without regard to
whether they are modifiable or not. The default is
Return the name of the currently executing file.
When called from outside an m-file return the empty string.
Given the argument
"fullpath", include the directory part of the
file name, but not the extension.
Given the argument
"fullpathext", include the directory part of
the file name and the extension.
Query or set the internal variable that controls whether Octave checks the time stamp on files each time it looks up functions defined in function files.
If the internal variable is set to
"system", Octave will not
automatically recompile function files in subdirectories of
octave-home/lib/version if they have changed since they were last compiled, but will recompile other function files in the search path if they change.
If set to
"all", Octave will not recompile any function files
unless their definitions are removed with
If set to
"none", Octave will always check time stamps on files to
determine whether functions defined in function files need to recompiled.
|• Manipulating the Load Path:|
|• Private Functions:|
|• Nested Functions:|
|• Overloading and Autoloading:|
|• Function Locking:|
|• Function Precedence:|
The ‘.m’ suffix was chosen for compatibility with MATLAB.