function

function [y1. yN] = myfun(x1. xM) declares a function named myfun that accepts inputs x1. xM and returns outputs y1. yN . This declaration statement must be the first executable line of the function. Valid function names begin with an alphabetic character, and can contain letters, numbers, or underscores.

With one output, brackets are optional: function y = myfun(x1. xM)
With no outputs, omit the equal sign: function myfun(x1. xM)
With no inputs, parentheses are optional: function [y1. yN] = myfun

You can save your function:

In a function file which contains only function definitions. The name of the file must match the name of the first function in the file.
In a script file which contains commands and function definitions. Script files cannot have the same name as a function in the file. Before R2024a: Local functions in scripts must be defined at the end of the file, after the last line of script code.

Files can include multiple local functions or nested functions. For readability, use the end keyword to indicate the end of each function in a file. The end keyword is required when:

Any function in the file contains a nested function.
The function is a local function within a function file, and any local function in the file uses the end keyword.
The function is a local function within a script file.

Examples

Function with One Output

Define a function in a file named calculateAverage.m that accepts an input vector, calculates the average of the values, and returns a single result.

function ave = calculateAverage(x) ave = sum(x(:))/numel(x); end

Call the function from the command line.

z = 1:99; ave = calculateAverage(z)

ave = 50

Function with Multiple Outputs

Define a function in a file named stat.m that returns the mean and standard deviation of an input vector.

function [m,s] = stat(x) n = length(x); m = sum(x)/n; s = sqrt(sum((x-m).^2/n)); end

Call the function from the command line.

values = [12.7, 45.4, 98.9, 26.6, 53.1]; [ave,stdev] = stat(values)

ave = 47.3400

stdev = 29.4124

Function Without Output

Define a function in a file named plotData.m that plots inputs using custom parameters.

function plotData(Xdata,Ydata) plot(Xdata,Ydata,Color="black",LineStyle="-.") end

Call the function from the command line.

Xdata = 1:100; Ydata = sin(pi/20*Xdata); plotData(Xdata,Ydata)

Figure contains an axes object. The axes object contains an object of type line.

Function in a Script File

Define a script in a file named integrationScript.m that computes the value of the integrand at $../../examples/matlab/win64/FunctionInAScriptFileExample_eq17815186678410134909.png\pi/3$$ and computes the area under the curve from 0 to $\pi$ . Include a local function that defines the integrand, $y = \sin(x)^3$ .

% Compute the value of the integrand at 2*pi/3. x = 2*pi/3; y = myIntegrand(x) % Compute the area under the curve from 0 to pi. xmin = 0; xmax = pi; f = @myIntegrand; a = integral(f,xmin,xmax) function y = myIntegrand(x) y = sin(x).^3; end

y = 0.6495 a = 1.3333