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7.2 Status of Variables

Command: clear options pattern ...

Delete the names matching the given patterns from the symbol table. The pattern may contain the following special characters:

?

Match any single character.

*

Match zero or more characters.

[ list ]

Match the list of characters specified by list. If the first character is ! or ^, match all characters except those specified by list. For example, the pattern ‘[a-zA-Z]’ will match all lower and upper case alphabetic characters.

For example, the command

clear foo b*r

clears the name foo and all names that begin with the letter b and end with the letter r.

If clear is called without any arguments, all user-defined variables (local and global) are cleared from the symbol table. If clear is called with at least one argument, only the visible names matching the arguments are cleared. For example, suppose you have defined a function foo, and then hidden it by performing the assignment foo = 2. Executing the command clear foo once will clear the variable definition and restore the definition of foo as a function. Executing clear foo a second time will clear the function definition.

This command may not be used within a function body.

Command: who options pattern ...

Command: whos options pattern ...

List currently defined symbols matching the given patterns. The following are valid options. They may be shortened to one character but may not be combined.

-all

List all currently defined symbols.

-builtins

List built-in variables and functions. This includes all currently compiled function files, but does not include all function files that are in the LOADPATH.

-functions

List user-defined functions.

-long

Print a long listing including the type and dimensions of any symbols. The symbols in the first column of output indicate whether it is possible to redefine the symbol, and whether it is possible for it to be cleared.

-variables

List user-defined variables.

Valid patterns are the same as described for the clear command above. If no patterns are supplied, all symbols from the given category are listed. By default, only user defined functions and variables visible in the local scope are displayed.

The command whos is equivalent to who -long.

Built-in Function: exist (name)

Return 1 if the name exists as a variable, 2 if the name (after appending ‘.m’) is a function file in the path, 3 if the name is a ‘.oct’ file in the path, or 5 if the name is a built-in function. Otherwise, return 0.

Built-in Function: document (symbol, text)

Set the documentation string for symbol to text.

Command: type options name ...

Display the definition of each name that refers to a function.

Normally also displays if each name is user-defined or builtin; the -q option suppresses this behaviour.

Currently, Octave can only display functions that can be compiled cleanly, because it uses its internal representation of the function to recreate the program text.

Comments are not displayed because Octave's parser currently discards them as it converts the text of a function file to its internal representation. This problem may be fixed in a future release.

Command: which name ...

Display the type of each name. If name is defined from a function file, the full name of the file is also displayed.