MATLAB Function Reference |
Remove items from workspace, freeing up system memory
Graphical Interface
As an alternative to the clear
function, use Clear Workspace in the MATLAB desktop Edit menu.
Syntax
clear clear name clear name1 name2 name3 ... clearglobal
name clear-regexp
expr1 expr2 ... clearglobal -regexp
expr1 expr2 ... clearkeyword
clear('name1','name2','name3',...)
Description
clear
removes all variables from the workspace. This frees up system memory.
clear name
removes just the M-file or MEX-file function or variable name
from the workspace. You can use wildcards (*
) to remove items selectively. For example, clear my*
removes any variables whose names begin with the string my
. It removes debugging breakpoints in M-files and reinitializes persistent variables, since the breakpoints for a function and persistent variables are cleared whenever the M-file is changed or cleared. If name
is global, it is removed from the current workspace, but left accessible to any functions declaring it global. If name
has been locked by mlock
, it remains in memory.
Use a partial path to distinguish between different overloaded versions of a function. For example, clear polynom/display
clears only the display
method for polynom
objects, leaving any other implementations in memory.
clear name1 name2 name3 ...
removes name1
, name2
, and name3
from the workspace.
clear
removes the global variable global
name
name
. If name
is global, clear name
removes name
from the current workspace, but leaves it accessible to any functions declaring it global. Use clear global name
to completely remove a global variable.
clear
clears all variables that match any of the regular expressions -regexp
expr1 expr2 ...
expr1
, expr2
, etc. This option only clears variables.
clear
clears all global variables that match any of the regular expressions global -regexp
expr1 expr2 ...
expr1
, expr2
, etc.
clear
clears the items indicated by keyword
keyword
.
Keyword |
Items Cleared |
all |
Removes all variables, functions, and MEX-files from memory, leaving the workspace empty. Using clear all removes debugging breakpoints in M-files and reinitializes persistent variables, since the breakpoints for a function and persistent variables are cleared whenever the M-file is changed or cleared. When issued from the Command Window prompt, also removes the Java packages import list. |
classes |
The same as clear all , but also clears MATLAB class definitions. If any objects exist outside the workspace (for example, in user data or persistent variables in a locked M-file), a warning is issued and the class definition is not cleared. Issue a clear classes function if the number or names of fields in a class are changed. |
functions |
Clears all the currently compiled M-functions and MEX-functions from memory. Using clear function removes debugging breakpoints in the function M-file and reinitializes persistent variables, since the breakpoints for a function and persistent variables are cleared whenever the M-file is changed or cleared. |
global |
Clears all global variables from the workspace. |
import |
Removes the Java packages import list. It can only be issued from the Command Window prompt. It cannot be used in a function. |
java |
The same as clear all , but also clears the definitions of all Java classes defined by files on the Java dynamic class path (see The Java Class Path in the External Interfaces documentation). If any java objects exist outside the workspace (for example, in user data or persistent variables in a locked M-file), a warning is issued and the Java class definition is not cleared. Issue a clear java command after modifying any files on the Java dynamic class path. |
variables |
Clears all variables from the workspace. |
clear('name1','name2','name3',...)
is the function form of the syntax. Use this form when the variable name or function name is stored in a string.
Remarks
When you use clear
in a function, it has the following effect on items in your function and base workspaces:
clear name
--If name
is the name of a function, the function is cleared in both the function workspace and in your base workspace.
clear
functions
--All functions are cleared in both the function workspace and in your base workspace.
clear
global
--All global variables are cleared in both the function workspace and in your base workspace.
clear
all
--All functions, global variables, and classes are cleared in both the function workspace and in your base workspace.
Limitations
clear
does not affect the amount of memory allocated to the MATLAB process under UNIX.
The clear
function does not clear Simulink models. Use close
instead.
Examples
Given a workspace containing the following variables
Name Size Bytes Class c 3x4 1200 cell array frame 1x1 java.awt.Frame gbl1 1x1 8 double array (global) gbl2 1x1 8 double array (global) xint 1x1 1 int8 array
you can clear a single variable, xint
, by typing
To clear all global variables, type
Using regular expressions, clear those variables with names that begin with Mon
, Tue
, or Wed
:
To clear all compiled M- and MEX-functions from memory, type clear functions
. In the case shown below, clear functions
was unable to clear one M-file function from memory, testfun
, because the function is locked.
clear functions % Attempt to clear all functions.inmem
ans = 'testfun' % One M-file function remains in memory.mislocked
testfun ans = 1 % This function is locked in memory.
Once you unlock the function from memory, you can clear it.
munlock
testfun
clear functions
inmem
ans =
Empty cell array: 0-by-1
See Also
clc
, close
, import
, inmem
, load
, mlock
, munlock
, pack
, persistent
, save
, who
, whos
, workspace
clc | clf |
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