fsolve first-order optimality

hi, i am confused about the first-order optimality in fsolve to solve the nonlinear equations. Is it neccessary for the first-order optimality to converge to zero when using fsove to solve the nonlinear equations? I find that the first-order optimality does not converge to zero when the iteration ceased, but the f(x) converges to zero, which pushed the iteration to stop. And in my code, the first-order optimality shows the trend to converge but stop at a large value in the last step of the iteration. Thank you a lot!

Answer 1

[Torsten]

Maybe this helps:

https://comp.soft-sys.matlab.narkive.com/23U8N4sP/first-order-optimality-for-fsolve