Not enough input arguments with fminunc

I wrote the followng code

global y t;

y = [1 2 4 6 4 12 11 13 11 14 16 17]';
T = length(y);
t = [1:T]';

x0 = [0, 0];
x = fminunc(@ssr, x0);

and function

function val = ssr(a, b)
    
    global y t;
    val = (y - a - b*t)'*(y - a - b*t);
    
end

when I run the code I get not enpugh input arguments error. I do not understand the reason. Could you help?

Answer 1

[Walter Roberson]

x = fminunc(@(x) ssr(x(1),x(2)), x0);

[Yasin Simsek]

thank you very much. It works. But I wonder why my code does not work. And I do not see the input arguments that you used in the documentation. Where can I learn it? Could you tell me?