Chapter 4: Programming in Matlab - College of the Redwoods

Section 4.6 Nested Functions in Matlab 401
We’ve seen a couple of ways we can fix this M-file so that the value of x is
printed by the subfunction. One way would be to declare the variable x global in
both the primary function and the subfunction.
function varScope1
global x
x=3;
nestfun1
function nestfun1
global x
fprintf(’In nestfun1, x equals: %d\n’,x)
Running this M-file produces the desired effect. The subfunction now has knowledge
of the global variable x and its fprintf statement is successful.
>> varScope1
In nestfun1, x equals: 3
We’ve also seen that we can pass the value of the variable x to an input argument
of the subfunction.
function varScope1
x=3;
nestfun1(x)
function nestfun1(x)
fprintf(’In nestfun1, x equals: %d\n’,x)
As readers can see, this also works.
>> varScope1
In nestfun1, x equals: 3
Nested Functions Redefine the Rules of Variable Scope. If we take our
same example, and nest the subfunction, a whole new set of rules are put into
place for variable scope, the first of which follows.