How to define a function with a summation

Hello,

I'm fairly new to matlab so I'm not too familiar with the way all of the functions work. I need to plot a function I have been given :

but I am having trouble defining it. I've tried the following:

syms k x
f = matlabFunction(b0 + symsum(a(k)*sin(k*x) + b(k)*cos(k*x)));

This gives me an error stating "Invalid indexing or function definition. Indexing must follow MATLAB indexing. Function arguments must be symbolic variables, and function body must be sym expression."

Can someone help me out? :)

[Sahil]

syms k x f = matlabFunction(b0 + symsum(a(k)*sin(k*x) + b(k)*cos(k*x)));

Answer 1

[Matt J]

An efficient implementation would be,

a=___;
b=___;
b0=___;
fplot(@(z) myFourier(z,a,b,b0));

function f=myFourier(x,a,b,b0)

   n=numel(a);
   arg=x(:).*(1:n);
   
   f=b0+sin(arg)*a(:)+cos(arg)*b(:);
   
   f=reshape(f,size(x));

end

[Rozalia Korycka]

Thanks a lot! It gives me a bunch of warnings but it does plot it so that's fine for my needs. I guess I wasn't even close... :)

[Matt J]

I'm baffled by the warnings. The function is vectorized as fplot requires.

[Rozalia Korycka]

That's exactly the opposite of what the warning says hahah but I don't know since I don't even know what is that supposed to mean