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A short arrow written above a letter, marking it as a vector.
Also known as: Vector notation, Arrow over a letter
Sometimes confused with: Vector hat
A short arrow written above a letter marks it as a vector rather than a scalar. Two other conventions do the same job: bold type, which is standard in printed textbooks, and a straight underline, which exists because handwriting and typewriting cannot produce bold. All three are current, and a reader moving between a printed text and a lecturer's board will meet two of them for the same quantity within an hour.
Marks a quantity as a vector — something with both magnitude and direction — rather than a scalar.
Contexts: Mathematics
Competes with two other conventions for the same job: bold type in printed work, and a straight underline, which exists precisely because a pen and a typewriter cannot produce bold.
Contexts: Mathematics
Is not the same as a caret above a letter, which marks a unit vector — one of length one — and is therefore a narrower claim than the arrow.
Contexts: Mathematics
A small horizontal arrow with a head at its right end, drawn directly above a single letter and no wider than it.
Both mark the kind of object a symbol stands for.