This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English verison of the page.

Note: This page has been translated by MathWorks. Please click here
To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.


Execute MATLAB expression in text


[output1,...,outputN] = eval(expression)


eval(expression) evaluates the MATLAB® code represented by expression. If you use eval within an anonymous function, nested function, or function that contains a nested function, the evaluated expression cannot create a variable.

[output1,...,outputN] = eval(expression) stores output from expression in the specified variables.

Input Arguments


Character vector or string scalar that contains a valid MATLAB expression.

To include a numeric value in the expression, convert it to a character vector or string scalar.

Output Arguments


Outputs from the evaluated expression.


collapse all

Select a matrix to plot at runtime.

This example requires that you have a matrix in the current workspace. For example:

aMatrix = magic(5);

Interactively request the name of a matrix to plot, and call eval to use its value.

expression = input('Enter the name of a matrix: ','s');
if (exist(expression,'var'))

If you type aMatrix at the input prompt, this code creates a mesh plot of magic(5).


  • Many common uses of the eval function are less efficient and are more difficult to read and debug than other MATLAB functions and language constructs. For more information, see Alternatives to the eval Function.

  • Whenever possible, do not include output arguments within the input to the eval function, such as eval(['output = ',expression]). The preferred syntax,

      output = eval(expression)

    allows the MATLAB parser to perform stricter checks on your code, preventing untrapped errors and other unexpected behavior.

Introduced before R2006a

Was this topic helpful?