Numerical Methods - Broyden's Method. Error: Not enough input arguments

Here is the code for broyden's method (found online):

function [xv,it]=broyden(x,f,n,tol)
% Broyden's method for solving a system of n non-linear equations
% in n variables.
%
% Example call: [xv,it]=broyden(x,f,n,tol)
% Requires an initial approximation column vector x. tol is required
% accuracy. User must define function f, for example see page 115.
% xv is the solution vector, parameter it is number of iterations
% taken. WARNING. Method may fail, for example, if initial estimates
% are poor.
%
fr=zeros(n,1); it=0; xv=x;
%Set initial Br
Br=eye(n);
fr=feval(f, xv);
while norm(fr)>tol
  it=it+1;
  pr=-Br*fr;
  tau=1;
  xv1=xv+tau*pr; xv=xv1;
  oldfr=fr; fr=feval(f,xv);
  %Update approximation to Jacobian using Broydens formula
  y=fr-oldfr; oldBr=Br;
  oyp=oldBr*y-pr; pB=pr'*oldBr;
  for i=1:n
    for j=1:n
      M(i,j)=oyp(i)*pB(j);
    end;
  end;
  Br=oldBr-M./(pr'*oldBr*y);
end;

How I am calling it:

x0 = [-0.5 1.4];
f = @(x,y) [(x+3)*(y^3-7)+18; sin(y*exp(x)-1)];

[xv, it] = broyden(x0, f, 15, 1e-9);

From this, I get the error:

Not enough input arguments.

Error in hw10>@(x,y)[(x+3)*(y^3-7)+18;sin(y*exp(x)-1)]

Error in hw10>broyden (line 55)
fr=feval(f, xv);

Error in hw10 (line 9)
[xv, it] = broyden(x0, f, 15, 1e-9);

I am not sure what the issue is here. The code stated that it worked for n x n non linear system. What am I missing here?

Thank you!

Answer 1

[Walter Roberson]

f = @(x,y) [(x+3)*(y^3-7)+18; sin(y*exp(x)-1)];

That is a function that needs two separate parameters. You are instead passing it a single vector. You need to add

f2 = @(x) f(x(1), x(2))

And pass that instead of f