…
►For examples of minimax polynomial approximations
to elementary and special
functions see
Hart et al. (1968).
…
►They satisfy the recurrence
relation
…
►
…
►Also, in cases where
satisfies a linear ordinary differential equation with polynomial coefficients, the expansion (
3.11.11) can be substituted in the differential equation
to yield a recurrence
relation satisfied by the
.
…
►A collection of minimax rational approximations
to elementary and special
functions can be found in
Hart et al. (1968).
…
…
► The analogous orthonormality is
…
►and completeness
relation
…
►
…
►Then orthogonality and normalization
relations are
…The formal completeness
relation is now
…
…
►Authors of the works appearing in the Digital Library of Mathematical
Functions (DLMF) have assigned copyright
to the works
to NIST, United States Department of Commerce, as represented by the Secretary of Commerce.
…
►The DLMF wishes
to provide users of special
functions with essential reference information
related to the use and application of special
functions in research, development, and education.
…Thus, we seek
to provide DLMF users with links
to sources of such software.
…
►
Index of Selected Software Within the DLMF Chapters
Within each of the DLMF chapters themselves we will provide a list of
research software for the functions discussed in that chapter.
The purpose of these listings is to provide references to the research
literature on the engineering of software for special functions.
To qualify for listing, the development of the software must have been the subject
of a research paper published in the peer-reviewed literature. If such software
is available online for free download we will provide a link to the software.
In general, we will not index other software within DLMF chapters unless
the software is unique in some way, such as being the only known software
for computing a particular function.
►
Master Software Index
In association with the DLMF we will provide an index of all software for the
computation of special functions covered by the DLMF. It is our intention that
this will become an exhaustive list of sources of software for special functions.
In each case we will maintain a single link where readers can obtain more information
about the listed software. We welcome requests from software authors
(or distributors) for new items to list.
Note that here we will only include software with capabilities that go beyond the
computation of elementary functions in standard precisions since such software is
nearly universal in scientific computing environments.
…
…
►For recurrence
relations for the coefficients in these expansions see
Frenkel and Portugal (2001, §3).
…
►The approximants are
elementary functions, Airy
functions, Bessel
functions, and parabolic cylinder
functions; compare §
2.8.
…
►With additional restrictions on
, uniform asymptotic approximations for solutions of (
28.2.1) and (
28.20.1) are also obtained in terms of
elementary functions by re-expansions of the Whittaker
functions; compare §
2.8(ii).
►Subsequently the asymptotic solutions involving either
elementary or Whittaker
functions are identified in terms of the Floquet solutions
(§
28.12(ii)) and modified Mathieu
functions
(§
28.20(iii)).
►For
related results see
Langer (1934) and
Sharples (1967, 1971).
…
…
►
§1.11(ii) Elementary Properties
…
►A similar
relation holds for the changes in sign of the coefficients of
, and hence for the number of negative zeros of
.
…
►The
elementary
symmetric functions of the zeros are (with
)
…
►Addition of
to each of these roots gives the roots of
.
…
►Add
to the roots of
to get those of
.
…
…
►For higher coefficients see
Baratella and Gatteschi (1988), and for another estimate of the error term in a
related expansion see
Wong and Zhao (2003).
…
►
In Terms of Elementary Functions
…
►For more powerful asymptotic expansions as
in terms of
elementary functions that apply uniformly when
,
, or
, where
and
is again an arbitrary small positive constant, see §§
12.10(i)–
12.10(iv) and
12.10(vi).
And for asymptotic expansions as
in terms of Airy
functions that apply uniformly when
or
, see §§
12.10(vii) and
12.10(viii).
With
the expansions in Chapter
12 are for the parabolic cylinder
function
, which is
related to the Hermite polynomials via
…
…
►
§3.10(ii) Relations to Power Series
…
►
Stieltjes Fractions
…
►For applications
to Bessel
functions and Whittaker
functions (Chapters
10 and
13), see
Gargantini and Henrici (1967).
…
►For
elementary functions, see §§
4.9 and
4.35.
…
►This forward algorithm achieves efficiency and stability in the computation of the convergents
, and is
related to the forward series recurrence algorithm.
…
…
►When the differences are moderately small, the iteration is stopped, the
elementary symmetric
functions of certain differences are calculated, and a polynomial consisting of a fixed number of terms of the sum in (
19.19.7) is evaluated.
…where the
elementary symmetric
functions
are defined by (
19.19.4).
…
►Legendre’s integrals can be computed from symmetric integrals by using the
relations in §
19.25(i).
…
►To (
19.36.6) add
…
►
§19.36(iii) Via Theta Functions
…