Let $U\subset\mathbb R^n$ be an open subset and $f:U\to \mathbb R$ be differentiable on $U$. The gradient of $f$ at $a \in U$ is the vector of the partial derivatives of $f$: \(\nabla f(a) = \left(\frac{\partial f}{\partial x_1}(a),\cdots, \frac{\partial f}{\partial x_n}(a) \right).\)
Wikidata ID: Q173582