MATLAB Programming

5 Types of Functions
Using a Subfunction
function h = sCountFun(X)
h = @subCount;
count = X
subCount(0, count);
function subCount(incr, ini)
persistent count;
initializing = nargin > 1;
if initializing
count = ini; else
count = count + incr
end
Using a Nested Function
function h = nCountFun(X)
h = @nestCount;
count = X
function nestCount(incr)
count = count + incr
end
end
When sCountFun executes, it passes the initial value for count to the
subCount subfunction. Keep in mind that the count variable in sCountFun is
not the same as the count variable in subCount; they are entirely independent
of each other. Whenever subCount is called via its function handle, the value
for count comes from its persistent place in memory.
In nestCount, thecount variable again gets its value from the primary
function when called from within the M-file. However, in this case the count
variable in the primary and nested functions are one and the same. When
nestCount is called by means of its function handle, the value for count is
assigned from its storage within the function handle.
Running the Example. The subCount and nestCount functions increment a
value in memory by another value that you pass as an input argument. Both
of these functions give the same results.
Get the function handle to nestCount, and initialize the count value to a
four-element vector:
h = nCountFun([100 200 300 400])
count =
100 200 300 400
Increment the persistent vector by 25, and then by 42:
h(25)
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