zh.wikipedia.org/wiki/凸優化
以下问题都是凸优化问题，或可以通过改变变量而转化为凸优化问题：[5]
Convex function
Convex minimization is a subfield of optimization that studies the problem of minimizing convex functions over convex sets. The convexity makes optimization easier than the general case since local minimum must be a global minimum, and first-order conditions are sufficient conditions for optimality.[1]
https://web.stanford.edu/~boyd/cvxbook/