Let $A^TA$ be a $n \times n$ matrix. I have the following quadratic program to solve: \begin{array}{rl} \min \limits_{x} & x^T A^T A x \\ \mbox{subject to} & \sum_{i=1}^{r} x_i =1, \sum_{i=r+1}^{s} x_i =1 \\ & x \ge 0 \end{array} where $n=r+s$
My question: what is the computational complexity of this problem ?