shewel function writing to find the global minimum with three variables

I am writting a Schewel function with three variables x1,x2 and x3 with x (-400,400), I am trying to find the global minimum of a schwefel function Can anybody tell me whats wrong with function code.

function output = objective_function(in)
x1 = in(1);
x2 = in(2);
x3 = in(3);
output=(-x1.*sin(sqrt(mod(x1)))+(-x2.*sin(sqrt(mod(x2)))+(-x3.*sin(sqrt(mod(x3)));
ouput=[F1 F2];
end

Answer 1

[Alan Stevens]

1. You probably want abs not mod.
2. You don't define F1 or F2 anywhere within the function
3. You have ouput not output in the last line.

[Maimona Adam]

Thank you very mcuh, F1 and F2 is the outcome that I want obtain from the optimazation if I am not wrong . does have to be defined ??