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 $f(a,b)$

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

See also

• Jacobi theta functions (notational variations) $\vartheta_{ij}(z;\tau), \vartheta_j(z), \theta_i(z;q)$