Belt filter

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 ${\mathrm{\Theta }}_{\mathrm{\Lambda }}(\tau )$, a holomorphic function on the upper half-plane
• Mock theta functions $\mu (q),f(q),\varphi (q),\psi (q),\chi (q)$, 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) ${\vartheta }_{ij}(z;\tau ),{\vartheta }_j(z),{\theta }_i(z;q)$