∫

The ∫ symbol is used to denote the integral in mathematics. The notation was introduced by the German mathematician Gottfried Wilhelm von Leibniz towards the end of the 17th century. The symbol was based on the ſ (long s) character, and was chosen because the integral is a limit of sums. See long s for more details on the history of ſ.

The ∫ symbol is U+222B in Unicode, \int in LaTeX. In HTML, it is written as ∫ (hexadecimal), ∫ (decimal) and ∫ (named entity).

The ∫ symbol is very similar to, but not to be confused with, the ʃ symbol (called esh).

Related symbols are ∬ (double integral, U+222C), ∭ (triple integral, U+222D), ∮ (contour integral, U+222E), ∯ (surface integral, U+222F), and ∰ (volume integral, U+2230).

[edit] References

Stewart, James (2003). "Integrals", Single Variable Calculus: Early Transcendentals, 5th edition, Belmont, CA: Brooks/Cole, 381. ISBN 0-534-39330-6. Retrieved on June 26, 2006.