Tau function may refer to:
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Tau function (integrable systems) Tau functions are an important ingredient in the modern mathematical theory of integrable systems, and have numerous applications in a variety of other domains. They were originally introduced by :simple:Ryogo Hirota, Ryogo Hirota in his ''direct me ...
, in integrable systems
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Ramanujan tau function
The Ramanujan tau function, studied by , is the function \tau : \mathbb \rarr\mathbb defined by the following identity:
:\sum_\tau(n)q^n=q\prod_\left(1-q^n\right)^ = q\phi(q)^ = \eta(z)^=\Delta(z),
where with , \phi is the Euler function, is th ...
, giving the Fourier coefficients of the Ramanujan modular form
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Divisor function
In mathematics, and specifically in number theory, a divisor function is an arithmetic function related to the divisors of an integer. When referred to as ''the'' divisor function, it counts the ''number of divisors of an integer'' (including ...
, an arithmetic function giving the number of divisors of an integer
{{disambiguation