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nargin

Number of function input arguments

Syntax

nargin
nargin(fun)

Description

example

nargin returns the number of function input arguments given in the call to the currently executing function. Use this syntax in the body of a function only.

example

nargin(fun) returns the number of input arguments that appear in the fun function definition. If the function includes varargin in its definition, then nargin returns the negative of the number of inputs. For example, if function myFun declares inputs a, b, and varargin, then nargin('myFun') returns -3.

Examples

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Create a function in a file named addme.m that accepts up to two inputs, and identify the number of inputs with nargin.

function c = addme(a,b)

switch nargin
    case 2
        c = a + b;
    case 1
        c = a + a;
    otherwise
        c = 0;
end

At the command prompt, call the addme function with two inputs.

c = addme(13,42)
c =

    55

Call the function with one input.

c = addme(13)
c =

    26

Determine how many inputs a function accepts.

The function addme created in the previous example has two inputs in its declaration statement (a and b).

fun = 'addme';
nargin(fun)
ans =
     2

Determine how many inputs a function that uses varargin can accept.

Define a function in a file named mynewplot.m that accepts numeric inputs x and y and any number of additional plot inputs using varargin.

function mynewplot(x,y,varargin)
   figure
   plot(x,y,varargin{:})
   title('My New Plot')
end

At the command line, query how many inputs newplot can accept.

fx = 'mynewplot';
nargin(fx)
ans =
    -3

The minus sign indicates that the third input is varargin. The mynewplot function can accept an indeterminate number of additional input arguments.

Input Arguments

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Function to return number of input arguments from its definition, specified as a function handle or a character vector.

Example: @cos

Example: 'plot'

Data Types: char | function_handle

Extended Capabilities

Introduced before R2006a

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