How can I fit data to a curve that is only defined implicitly

Hello everyone, I am learning how to fit data to a curve that is only defined implicitly. For practice, I am using the function below:

function yout = myImplicitF(x,AB)
    x0 = 0.01;
    y0 = 0.01;
    A=AB(1);
    B=AB(2);
    yout = zeros(size(x));
    opt = optimset('display','off');
    for i=1:length(x)
        yout(i) = fsolve(@(y) x(i)- (x0 -(y + B*log(y/y0)+y0)/A), .1, opt); 
    end

      xdata = -5:.1:1;
      y = myImplicitF(x,[1 1]) + randn(size(x))/100;

      params = [A B];
      lsqcurvefit(@(params, xdata) myImplicitF(xdata,params),[0.1 0.1], x, y)

      fprintf(1,'\tparams:\n')
  for k1 = 1:length(p)
      fprintf(1, '\t\tP(%d) = %8.5f\n', k1, p(k1))
  end

ezplot(@(x)myImplicitF(x,[1 1]),[-5 1])

end

which gives an error message:

>> myImplicitF
Not enough input arguments.

Error in myImplicitF (line 4)
    A=AB(1);

Where am I going wrong?