" s = svds(Afun,n,...) specifies a function handle Afun instead of a matrix. The second input n gives the size of matrix A used in Afun."
You will notice that in the help page, the input Afun is a link. When you click on that link it scrolls down the page to the section that specifies how the function must be defined. There it states:
"The function Afun must satisfy these conditions:"
- " Afun(x,'notransp') accepts a vector x and returns the product A*x."
- " Afun(x,'transp') accepts a vector x and returns the product A'*x."
Your function does not support either of those two conditions (in fact your function does not support any second argument at all, thus the error message). You will need to write your function to accept a second input argument and return appropriate values, as per the documentation.
