Not enough input arguments.

I have a file called F.m which contains the following code:

1    % INPUT:
2    % 3D vector x
3    %
4    % OUTPUT:
5    % function value at x
6    
7    function val = f(x)
8        val= x(1)^2 + x(1)*x(2)^3 - 12*x(3) + 4;
9    end

I am trying to call F.m in an algorithm in another file, but when I run the code, I get the following error:

"Error using F (line 8) Not enough input arguments."

I'm new to MATLAB, so I'm not sure what I'm doing wrong here. Any help would be greatly appreciated!

[Aaron Powers]

Could you include the code that calls your function f, with an example of what x is?

[Anonymous Chupacabra]

Thank you for your interest in my question, Aaron!

x is a 3D point/vector, for example x = (x(1), x(2), x(3)) = (0,1,2).

Here's the code (it also calls on 2 other algorithms and requires input of other values too):

function [xminest, fminest,k] = Algorithm1(f, gradf, x0, tol1, tol2, T)

k = 0;
xk = x0;

while ( norm(feval(gradf, xk)) >= tol1 )

      %du = feval(gradf, xk);
      %dk = -du/norm(du);
      dk = -1*feval(gradf, xk);

              [a, b] = Algorithm2(f, xk, dk, T);

              [tmin, fmin] = Algorithm3(f, a, b, tol2, xk, dk);

               k = k + 1;
               xk = xk + tmin*dk;

end
    fminest = feval(f,xminest);

To run the code, I enter the command:

Algorithm1(F, gradf, [0,1,2], 0.1, 0.1, 10)

Answer 1

[the cyclist]

With the syntax

Algorithm1(F, gradf, [0,1,2], 0.1, 0.1, 10)

MATLAB is looking for a variable named F (and similarly with gradf). You need to tell it that F is a function, by passing the function handle:

Algorithm1(@F, @gradf, [0,1,2], 0.1, 0.1, 10)

It looks like you have similar problems deeper in your code, but I could not resolve them completely because I don't have all the functions you are using.

[Anonymous Chupacabra]

Thank you very much, cyclist! After prefacing each file name with @ as you said, the code is executing as intended!

Answer 2

[Jan]

Inside this line:

[a, b] = Algorithm2(f, xk, dk, T);

you call the function "f" without arguments. But You want top provide the function handle of this file instead:

[a, b] = Algorithm2(@f, xk, dk, T);

Note: In modern Matlab versions you can omit the feval and call the function handle directly, which looks nicer:

while norm(gradf(xk)) >= tol1

[Anonymous Chupacabra]

Thank you very much, Jan! Using the function handle as you showed worked! Thank you also for your tip, as I have the 2015 MATLAB version, but I think the algorithm code I am using may be quite old.