Theta function (disambiguation)

Theta functions $$\vartheta(z;\tau)$$ are special functions of several complex variables. Theta function may also refer to:

Jacobi-related functions

 * q-theta function, $$\theta(z;q)$$, a type of q-series
 * Theta function of a lattice, $$\Theta_\Lambda(\tau)$$, a holomorphic function on the upper half-plane
 * Mock theta functions, $$\mu(q), f(q), \phi(q), \psi(q), \chi(q)$$, etc., a mock modular form of weight 1/2
 * Ramanujan theta function, $$f(a,b)$$
 * Neville theta functions

Other functions

 * Riemann–Siegel theta function, $$\theta(t)$$
 * Chebyshev function, $$\vartheta(x)$$
 * Feferman's function, $$\theta_\alpha(\beta)$$
 * Heaviside step function, sometimes denoted $$\theta(x)$$
 * Lovász theta function, an upper bound on the Shannon capacity of a graph