MATLAB: Do I get error, “Not enough input arguments”

argumentsdefine functionsMATLAB

Dear Group,
I am trying to estimate parameters from a non-linear model using lsqnonlin.
My function is
function F = myfun(x,y,X)
F = (y - (1 + x(1)*(x(2)/0.0025662))*X(:,1) - (1-x(1)^2)*(x(2)/x(3))*X(:,2) - x(4)*X(:,3))
end
y = is a column vector of 18026 observation
X is a matrix with 3 columns each with 18026 observations
x is my parameter matrix (I have four parameters - x(1), x(2), x(3), and x(4), to estimate.
x0 = [-0.06,0.6,0.006,0.85] are my initial values.
My parameters have upper and lower bounds:
lb = [-1,0,0,-1]
ub = [1,2,2,2]
Because I get different estimates when I use lsqnonlin as I change starting values, I wish to the multiple starting values feature of MATLAB to get a global minimum.
I am using this URL to write the code to feed multiple starting values: https://fr.mathworks.com/help/gads/multistart-using-lsqcurvefit-or-lsqnonlin.html
When I submit
problem = createOptimProblem('lsqnonlin','objective',myfun, 'xdata',X,'ydata',y, 'x0',x0,'lb',lb,'ub',ub);
I get the following error message:
 Not enough input arguments.
 Error in myfun (line 2)
 F = (y - (1 + x(1)*(x(2)/0.0025662))*X(:,1) - (1-x(1)^2)*(x(2)/x(3))*X(:,2) -  x(4)*X(:,3))
Can you kindly point out the error in my set up. Thanks!
best, Srinivasan Rangan

Best Answer

                                                         | This is the problem
                                                         V
  problem = createOptimProblem('lsqnonlin', 'objective', @myfun, ...
                               'xdata',X,'ydata',y, 'x0',x0,'lb',lb,'ub',ub);
Using myfun only calls this function without input arguments, while @myfun provides the function handle.
Related Question