# Writing “$\nabla f$” or “$\operatorname{grad} f$”

When hand-writing the gradient of $f$ as "$\nabla f$" or "grad $f$", is it necessary to indicate that it is a vector using the usual vector markings (cap, arrow, wavy line, etc.)?

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Writing $\nabla f$ or ${\rm grad}\, f$ is sufficient. Avoid "vector markings" and use bold face if you want to enhance the fact that you are talking about a vector here; like ${\bf x}=(x_1,\ldots, x_n)$. –  Christian Blatter Sep 27 '12 at 18:36
@christian Thanks, got it. –  Ryan Sep 27 '12 at 18:39
You use bold face in hand writing? –  GEdgar Sep 27 '12 at 19:25

It should be considered obligatory to write, for example $\vec{a}$ or $\mathbf{a}$, when you're writing in a context in which vectors and vector-valued functions are generally written that way. But that is not always done. The style should be consistent throughout the document.
However, notice that the $f$ in $\nabla f$ is scalar-valued. The expression $\nabla f$ is vector-valued, and that is indicated by the meanings of the symbols.