What does $\mathbb{R}_{++}$ mean?
I know $\mathbb{R}_+$ means all non-negative real numbers, but I have no clue what $\mathbb{R}_{++}$ means.
What does $\mathbb{R}_{++}$ mean?
I know $\mathbb{R}_+$ means all non-negative real numbers, but I have no clue what $\mathbb{R}_{++}$ means.