clear — Clear variables from the active workspace in MATLAB and RunMat.
clear removes variables from the active workspace. It supports clear, clear all, and named-variable forms (for example clear x), following MATLAB and RunMat workspace-clearing semantics.
Syntax
clear()
clear(name, ...)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
name | StringScalar | Variadic | — | Variable names to clear. 'all' clears entire workspace. |
Returns
| Name | Type | Description |
|---|---|---|
ans | NumericArray | Empty 0x0 return value. |
Errors
| Identifier | When | Message |
|---|---|---|
| — | Character-array argument is not a row vector. | clear: character array inputs must be a row vector or scalar text value |
| — | A target argument is not a string scalar/array or row character vector. | clear: expected variable names as character vectors or string scalars |
How clear works
clearwith no inputs clears all workspace variables created in the current session.clear('all')and command-formclear allare treated the same as bareclear.clear xremoves the variablexwhile leaving other workspace bindings intact.- Multiple names can be supplied as separate inputs or command-form tokens, for example
clear x y z. - Active
onCleanupobjects are invoked before their workspace bindings are removed. - After a successful clear, removed variables are no longer available to later statements and the workspace snapshot is refreshed so hosts can drop cleared bindings.
- Accepts variable names as string scalars, row character vectors, or string arrays. If any input is
all, the entire workspace is cleared. - Clearing a name that does not exist is a no-op.
clearis a sink builtin and does not produce a meaningful output value.
Does RunMat run clear on the GPU?
clear performs host-side workspace mutation only. It does not launch GPU kernels, does not participate in fusion, and does not depend on acceleration providers.
Examples
Clear the entire interactive workspace
x = 1;
y = magic(3);
clearExpected output:
% x and y are removed from the workspaceUse MATLAB-style command form
a = 42;
clear allExpected output:
% a is removed from the workspaceAccessing a cleared variable raises an error
x = 7;
clear;
xExpected output:
Undefined variable: xClear one variable while leaving others intact
x = 1;
y = 2;
clear xExpected output:
% x is removed from the workspace while y remains definedClear multiple named variables in command form
a = 1;
b = 2;
c = 3;
clear a bExpected output:
% a and b are removed; c remains definedUsing clear with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how clear changes the result.
Run a small clear example, explain the result, then change one input and compare the output.
FAQ
Does clear remove every variable in the current session?⌄
Bare clear and clear all clear the full workspace. Named forms such as clear x remove only the specified bindings.
Can I clear only one variable?⌄
Yes. Use clear x or clear("x") to remove one variable, and pass multiple names to clear more than one binding in a single call.
Does clear return anything?⌄
No meaningful value is returned. clear is a side-effecting builtin whose purpose is to mutate workspace state.
Does clear affect plotting state or the console?⌄
No. clear only clears workspace variables. Use plotting commands such as close all for figures and clc for the visible console.
Does GPU residency matter?⌄
No. clear operates on session bookkeeping, not on array kernels or provider-managed computations.
Related Introspection functions
addprop · assignin · class · clearAllMemoizedCaches · clearCache · clearvars · dbclear · dbstack · dbstatus · dbtype · evalc · feval · findprop · getcallinfo · inputParser · isa · ischar · isdeployed · iskeyword · ismethod · isobject · isstring · isUnderlyingType · keyboard · matlab.metadata.DynamicProperty.delete · memoize · metaclass · mislocked · mlock · munlock · namelengthmax · narginchk · nargoutchk · notify · onCleanup · stats · str2func · superclasses · underlyingType · verLessThan · version · which · who · whos
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how clear is executed, line by line, in Rust.
- View the source for clear in Rust on GitHub
- Learn how the RunMat runtime works
- Found a bug? Open an issue with a minimal reproduction.
About RunMat
RunMat is an open-source runtime that executes MATLAB-syntax code blazing on any GPU. It is licensed under the Apache 2.0 license.
- RunMat automatically optimizes your math for GPU execution on Apple, Nvidia, and AMD hardware. No code changes needed. Simulations that took hours now take minutes.
- Start running code in seconds. RunMat runs in the browser, on the desktop, or from the CLI. No license server, no IT ticket.