| context | $n\in\mathbb N$ |
| definiendum | $ A \in \mathrm{it}(n) $ |
| postulate | $ A \in \mathrm{SquareMatrix}(n,\mathbb C) $ |
| $ x \in \text{ColumnVector}(n,\mathbb C) $ |
| postulate | $ A \in \mathrm{SquareMatrix}(n,\mathbb C) $ |
| postulate | $ x^* A\ x \ge 0 $ |
Wikipedia: Positive-definite matrix