How to put fsolve in a loop, using 2 unknowns?

Question

Noob 2021-6-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/861785-how-to-put-fsolve-in-a-loop-using-2-unknowns

编辑： Sargondjani 2021-6-23

Hi,

I want to write a code that asks fsolve to go through some combinations of guesses and then find all the roots (xdot, ydot) to the equation, but I'm having some trouble debugging the code. I defined the function locally, without saving it in a separate file.

Thanks in advance,

H = @(xdot, ydot) fsolve_root_finding(xdot, ydot);
for xdot = linspace(1,5,5)
  for ydot = linspace(-5,-1,5)
    [ my_root, fval, exit_flag ] = fsolve( H, [ xdot, ydot ] )
    plot( my_root, 'bx','MarkerSize',10 ); 
  end
  hold on
end
   
function G = fsolve_root_finding(xdot, ydot)
  G(1) = xdot + ydot;
end

Here's the current error message:

Not enough input arguments.
Error in fsolve_practice>@(xdot,ydot)fsolve_root_finding(xdot,ydot)
Error in fsolve (line 242)
            fuser = feval(funfcn{3},x,varargin{:});
Error in fsolve_practice (line 9)
[ my_root, fval, exit_flag ] = fsolve( H, [ xdot, ydot ] )
Caused by:
    Failure in initial objective function evaluation. FSOLVE cannot continue.