MATLAB Programming

Nested Functions
Variable Scope in Nested Functions
The scope of a variable is the range of functions that have direct access to the
variable to set, modify, or acquire its value. When you define a local (i.e.,
nonglobal) variable within a function, its scope is normally restricted to that
function alone. For example, subfunctions do not share variables with the
primary function or with other subfunctions. This is because each function
and subfunction stores its variables in its own separate workspace.
Like other functions, a nested function has its own workspace. But it also has
access to the workspaces of all functions in which it is nested. So, for example,
a variable that has a value assigned to it by the primary function can be read
or overwritten by a function nested at any level within the primary. Similarly,
a variable that is assigned in a nested function can be read or overwritten by
any of the functions containing that function.
In the following two examples, variable x is stored in the workspace of the
outer varScope function and can be read or written to by all functions nested
within it.
function varScope1
x = 5;
nestfun1
function nestfun1
nestfun2
function nestfun2
x = x + 1
end
end
end
function varScope2
nestfun1
function nestfun1
nestfun2
function nestfun2
x = 5;
end
end
x = x + 1
end
As a rule, a variable used or defined within a nested function resides in the
workspace of the outermost function that both contains the nested function
and accesses that variable. The scope of this variable is then the function to
which this workspace belongs, and all functions nested to any level within
that function.
In the next example, the outer function, varScope3, does not access variable x.
Following the rule just stated, x is unknown to the outer function and thus is
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