Help with nesting subfunctions?

I have an assignment that requires me to use a nested subfunction to produce a plot, and am not sure how to incorporate it. The exact problem states:

Recall Euler’s formula from analytical calculus: ei·x = cos(x) + i · sin(x), where i is the imaginary unit. A slight rearrangement yields:

cos(x) = ei·x − i · sin(x)

Create a nested subfunction that accepts one input argument x (which may be
a vector) and returns the cos function defined as above. Call this function and plot its output from −π ≤ x ≤ π using π/100 increments. Label axes and title it ”Euler Output”.

So far, I have not even been able to do this without a nested subfunction. MATLAB tells me that, "Subscript indices must either be real positive integers or logicals," but the given equation clearly needs to make use of imaginary roots.

[Robert Cumming]

post some of your code to show us what you have done.

[Tyler]

%% Part 1 - Euler

x=-pi:pi/100:pi;

cos(x)=exp(1i.*x)-1i*sin(x);

figure1(x,cos(x));

title('Euler Output')

And that returns with

"Subscript indices must either be real positive integers or logicals."

[Tyler]

I know that isn't a nested function at all, but shouldn't that still work just so I can get an idea of which direction to go?

Answer 1

[Wayne King]

Your problem is here:

 cos(x)=exp(1i.*x)-1i*sin(x);

You should spend some time reading the MATLAB Getting Started material, but you just assign the output to a variable.

   cosx = exp(1i*x)-1i*sin(x);

Of course you have another problem with figure1( ) unless you have written a function called figure1().

[Tyler]

How would I go about making that an anonymous function and calling it through the script? Just by making the above:

h=@cosx exp(1i*x)-1i*sin(x);

?

What benefit does that have when writing code?

[Wayne King]

 cosx =@(x) exp(1i*x)-1i*sin(x);

that gives you a function handle.

Then you can do:

x = -pi:0.01:pi;
y = cosx(x);