# §13.18 Relations to Other Functions

## §13.18(ii) Incomplete Gamma Functions

For the notation see §§6.2(i), 7.2(i), and 8.2(i). When is an integer the Whittaker functions can be expressed as incomplete gamma functions (or generalized exponential integrals). For example,

Special cases are the error functions

13.18.7

## §13.18(iii) Modified Bessel Functions

When the Whittaker functions can be expressed as modified Bessel functions. For the notation see §§10.25(ii) and 9.2(i).

## §13.18(v) Orthogonal Polynomials

Special cases of §13.18(iv) are as follows. For the notation see §18.3.