Is there any current method of distinguishing a local and a global extrema?

46 Views Asked by At

Given an arbitrary multivariate function $f(x)$ in $\mathbb{R}^n$ I was wondering if there is any method of distinguishing between a local minimum and a global minimum given you already have a point at which $f'(x)=0$ and $f''(x) > 0$. I believe its an unsolvable problem but I'm not sure, perhaps there's an approach from Calculus of Variation?