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14 Legendre and Related FunctionsNotation

§14.1 Special Notation

(For other notation see Notation for the Special Functions.)

x, y, \tau real variables.
z=x+iy complex variable.
m, n unless stated otherwise, nonnegative integers, used for order and degree, respectively.
\mu, \nu general order and degree, respectively.
-\frac{1}{2}+i\tau complex degree, \tau\in\mathbb{R}.
\gamma Euler’s constant (§5.2(ii)).
\delta arbitrary small positive constant.
\psi\left(x\right) logarithmic derivative of gamma function (§5.2(i)).
\psi'\left(x\right) \ifrac{\mathrm{d}\psi\left(x\right)}{\mathrm{d}x} .
\mathbf{F}\left(a,b;c;z\right) Olver’s scaled hypergeometric function: \ifrac{F\left(a,b;c;z\right)}{\Gamma\left(c\right)}.

Multivalued functions take their principal values (§4.2(i)) unless indicated otherwise.

The main functions treated in this chapter are the Legendre functions \mathsf{P}_{\nu}\left(x\right), \mathsf{Q}_{\nu}\left(x\right), P_{\nu}\left(z\right), Q_{\nu}\left(z\right); Ferrers functions \mathsf{P}^{\mu}_{\nu}\left(x\right), \mathsf{Q}^{\mu}_{\nu}\left(x\right) (also known as the Legendre functions on the cut); associated Legendre functions P^{\mu}_{\nu}\left(z\right), Q^{\mu}_{\nu}\left(z\right), \boldsymbol{Q}^{\mu}_{\nu}\left(z\right); conical functions \mathsf{P}^{\mu}_{-\frac{1}{2}+i\tau}\left(x\right), \mathsf{Q}^{\mu}_{-\frac{1}{2}+i\tau}\left(x\right), \widehat{\mathsf{Q}}^{\mu}_{-\frac{1}{2}+i\tau}\left(x\right), P^{\mu}_{-\frac{1}{2}+i\tau}\left(x\right), Q^{\mu}_{-\frac{1}{2}+i\tau}\left(x\right) (also known as Mehler functions).

Among other notations commonly used in the literature Erdélyi et al. (1953a) and Olver (1997b) denote \mathsf{P}^{\mu}_{\nu}\left(x\right) and \mathsf{Q}^{\mu}_{\nu}\left(x\right) by \mathrm{P}_{\nu}^{\mu}(x) and \mathrm{Q}_{\nu}^{\mu}(x), respectively. Magnus et al. (1966) denotes \mathsf{P}^{\mu}_{\nu}\left(x\right), \mathsf{Q}^{\mu}_{\nu}\left(x\right), P^{\mu}_{\nu}\left(z\right), and Q^{\mu}_{\nu}\left(z\right) by P_{\nu}^{\mu}(x), Q_{\nu}^{\mu}(x), \mathfrak{P}_{\nu}^{\mu}(z), and \mathfrak{Q}_{\nu}^{\mu}(z), respectively. Hobson (1931) denotes both \mathsf{P}^{\mu}_{\nu}\left(x\right) and P^{\mu}_{\nu}\left(x\right) by P^{\mu}_{\nu}\left(x\right); similarly for \mathsf{Q}^{\mu}_{\nu}\left(x\right) and Q^{\mu}_{\nu}\left(x\right).