Nabla symbol

The nabla is a triangular symbol like an inverted Greek delta:${\displaystyle \nabla }$ or ∇. The name comes, by reason of the symbol's shape, from the Hellenistic Greek word νάβλα for a Phoenician harp, and was suggested by the encyclopedist William Robertson Smith to Peter Guthrie Tait in correspondence.

The nabla symbol is available in standard HTML as ∇ and in LaTeX as \nabla. In Unicode, it is the character at code point U+2207, or 8711 in decimal notation.

It is also called del.

The differential operator given in Cartesian coordinates ${\displaystyle \{x,y,z\}}$ on three-dimensional Euclidean space by

was introduced in 1837 by the Irish mathematician and physicist William Rowan Hamilton, who called it ◁. (The unit vectors ${\displaystyle \{\mathbf {i} ,\mathbf {j} ,\mathbf {k} \}}$ were originally Hamilton's unit quaternions.) The mathematics of ∇ received its full exposition at the hands of Tait.

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