Types of Functions
In this section...
“Local and Nested Functions in a File” on page 20-17
“Private Functions in a Subfolder” on page 20-18
“Anonymous Functions Without a File” on page 20-18
Local and Nested Functions in a File
Program files can contain multiple functions. Local and nested functions are useful for dividing
programs into smaller tasks, making it easier to read and maintain your code.
Local functions are subroutines that are available within the same file. Local functions are the most
common way to break up programmatic tasks. In a function file, which contains only function
definitions, local functions can appear in the file in any order after the main function in the file. In a
script file, which contains commands and function definitions, local function must be at the end of the
file. (Functions in scripts are supported in R2016b or later.)
For example, create a function file named myfunction.m that contains a main function,
myfunction, and two local functions, squareMe and doubleMe:
function b = myfunction(a)
b = squareMe(a)+doubleMe(a);
end
function y = squareMe(x)
y = x.^2;
end
function y = doubleMe(x)
y = x.*2;
end
You can call the main function from the command line or another program file, although the local
functions are only available to myfunction:
myfunction(pi)
ans =
16.1528
Nested functions are completely contained within another function. The primary difference between
nested functions and local functions is that nested functions can use variables defined in parent
functions without explicitly passing those variables as arguments.
Nested functions are useful when subroutines share data, such as applications that pass data
between components. For example, create a function that allows you to set a value between 0 and 1
using either a slider or an editable text box. If you use nested functions for the callbacks, the slider
and text box can share the value and each other’s handles without explicitly passing them:
function myslider
value = 0;
f = figure;
s = uicontrol(f,'Style','slider','Callback',@slider);
e = uicontrol(f,'Style','edit','Callback',@edittext,...
Types of Functions
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