Alternative for a for loop. How would I write this code without using a for loop?

function approx = approxCosineFunction(x, t)
    approx=1;
    for i=1:1:t-1
        addterm = (-1)^i*(x^(2*i))/factorial(2*i);
        approx = approx + addterm;
    end
end

[Matt J]

There are already no for loops in the code that you've shown.

[John Barber]

oops. Fixed it

Answer 1

[James Tursa]

To get the correct result, you need to make that divide an element-wise divide, and then add up the resulting terms into approx. E.g.,

addterm = (-1).^(1:1:t-1).*(x.^(2.*(1:1:t-1)))./factorial(2.*(1:1:t-1));  % <-- changed / to ./
approx = approx + sum(addterm);  % <-- added the sum( )

But this will just give you the last approximation. If you wanted to return a vector containing all of the intermediate results as well, you could use cumsum instead. E.g.,

approx = approx + cumsum(addterm);