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functions

Information about function handle

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Syntax

s = functions(fh)

Description

s = functions(fh) returns information about a function handle. This information includes the function name, type, and file name.

Use the functions function for querying and debugging purposes only.

Note

Do not use functions programmatically because its behavior could change in subsequent MATLAB® releases.

example

Examples

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Open Live Script

Create a function handle and display its information.

fh = @cos;
s = functions(fh)
s = struct with fields:
    function: 'cos'
        type: 'simple'
        file: ''

Create a function handle to an anonymous function. Display its information and values of required variables.

Create a handle to the function x2 + y, and invoke the function using the handle.

y = 7;
fh = @(x)x.^2+y;
z = fh(2)
z =

    11

Display information about the function handle.

s = functions(fh)
s = 

            function: '@(x)x.^2+y'
                type: 'anonymous'
                file: ''
           workspace: {[1x1 struct]}
    within_file_path: '__base_function'

The function handle contains the required value of y.

s.workspace{1}
ans = 

    y: 7

Create a function that returns handles to local and nested functions. Display their information.

Create the following function in a file, functionsExample.m, in your working folder. The function returns handles to a nested and local function.

function [hNest,hLocal] = functionsExample(v)

hNest = @nestFunction;
hLocal = @localFunction;

    function y = nestFunction(x)
        y = x + v;
    end

end

function y = localFunction(z)
y = z + 1;
end

Invoke the function.

[hNest,hLocal] = functionsExample(13)
hNest = 

    @functionsExample/nestFunction


hLocal = 

    @localFunction

Display information about the handle to the nested function.

s1 = functions(hNest)
s1 = 

     function: 'functionsExample/nestFunction'
         type: 'nested'
         file: 'C:\work\functionsExample.m'
    workspace: {[1x1 struct]}

Display information about the handle to the local function.

s2 = functions(hLocal)
s2 = 

     function: 'localFunction'
         type: 'scopedfunction'
         file: 'C:\work\functionsExample.m'
    parentage: {'localFunction'  'functionsExample'}

Input Arguments

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Handle to query, specified as a function handle.

Output Arguments

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Information about a function handle, returned as a structure. The structure contains the following fields.

Field Name

Field Description

function

Function name. If the function associated with the handle is a nested function, the function name takes the form main_function/nested_function.

type

Function type. For example 'simple', 'nested', 'scopedfunction', or 'anonymous'.

file

Full path to the function with the file extension.

  • If the function is a local or nested function, then file is the full path to the main function.

  • If the function is a built-in MATLAB function, then file is an empty character array ('').

  • If the function is an anonymous function and defined in the command line or in a file not on the MATLAB path, then file is an empty character array ('').

  • If the function is an anonymous function and defined in a file on the MATLAB path, then file is the full path to the file.

  • If you load a saved function handle, then file is an empty character array ('').

  • If the function is a class method, then file is an empty character array ('').

The structure has additional fields depending on the type of function associated with the handle. For example, a local function has a parentage field, and an anonymous function has a workspace field. Use the information in s for querying and debugging purposes only.

Extended Capabilities

Version History

Introduced before R2006a

See Also

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