Help with nesting subfunctions?

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Tyler
Tyler 2012-9-25
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.
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Tyler
Tyler 2012-9-25
%% 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
Tyler 2012-9-25
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?

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Wayne King
Wayne King 2012-9-25
编辑：Wayne King 2012-9-25
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().
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Tyler
Tyler 2012-9-25
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
Wayne King 2012-9-25
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);

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