Let $f(x): \mathbb{C}^M \rightarrow R$ be a continuously differentiable function of complex vector $x$. Besides, let us assume that $\{x_n\}$ is a sequence of $x$. If we know that sequence $\{f(x_n)\}$ converges to a value (less than $\infty$), can we claim that $\{x_n\}$ also converges?
Note: we also know that $\{f(x_n)\}$ is increasing and bounded from the top.