# Nabla

Mathematical signs
arithmetic
Plus sign +
Minus sign - , ./.
Mark , ×
Divided sign : , ÷ , /
Plus minus sign ± ,
Comparison sign < , , = , , >
Root sign
Percent sign %
Analysis
Sum symbol Σ
Product mark Π
Difference sign , Nabla ,
Prime
Partial differential
Integral sign
Concatenation characters
Infinity symbol
geometry
Angle sign , , ,
Vertical , parallel ,
Triangle , square ,
Diameter sign
Set theory
Union , cut ,
Difference , complement ,
Element character
Subset , superset , , ,
Empty set
logic
Universal quantifier
Existential quantifier
Conjunction , disjunction ,
Negation sign ¬

The symbol Nabla (∇) is a mathematical symbol that is mainly used in vector analysis to denote the Nabla operator . In addition, it is used in differential geometry to denote the relationship or the covariant derivative .

## description

The symbol Nabla is not a letter, but arose from similar symbols of the quaternion analysis by William Rowan Hamilton . Peter Guthrie Tait introduced today's form of an upside-down delta Δ. The name "Nabla" comes from the theologian William Robertson Smith (1846-1894), who derived the form from the biblical lyre Nevel ( Hebrew נבל nével , ancient Greek νάβλα nábla , Latin nablium ).

The Nabla is identical to the symbol for water in the ancient four-element teaching . However, there is neither a substantive nor a historical relationship between the two symbols.

The character Nabla can be represented in HTML as `&nabla;`and in LaTeX as `\nabla`. In the Unicode character set, it has the symbol number 8711 ( hexadecimal 0x2207).

## Individual evidence

1. ^ Manfredo Perdigão do Carmo: Riemannian Geometry. Birkhäuser, Boston 1992, ISBN 0-8176-3490-8 , p. 50.
2. Capt. DRDerret, Dr. CBBarrass: Ship Stability for Masters and Mates Elsevier Butterworth-Heinemann, 5th Edition, ISBN 0-7506-4101-0 , p. 378.
3. Dubasi Govardhana Rao: Introduction to Biochemical Engineering . Tata McGraw-Hill Education, 2010, ISBN 978-0-07-015138-3 ( google.de [accessed February 7, 2019]).