This is the hypergeometric differential equation. It has regular
singularities at
, with corresponding exponent pairs
,
,
, respectively. When none of the exponent
pairs differ by an integer, that is, when none of
,
,
is an
integer, we have the following pairs
,
of fundamental
solutions. They are also numerically satisfactory (§2.7(iv)) in
the neighborhood of the corresponding singularity.
(a) If
equals
, and
, then
fundamental solutions in the neighborhood of
are given by
(15.10.2) with the interpretation (15.2.5) for
.
(b) If
equals
, and
, then
fundamental solutions in the neighborhood of
are given by
and

or

or

(c) If the parameter
in the differential equation equals
, then fundamental solutions in the
neighborhood of
are given by
times those in (a) and (b),
with
and
replaced throughout by
and
, respectively.
(d) If
equals
, or
, then
fundamental solutions in the neighborhood of
are given by those in
(a), (b), and (c) with
replaced by
.
(e) Finally, if
equals
, or
, then
fundamental solutions in the neighborhood of
are given by
times those in (a), (b), and (c) with
and
replaced by
and
, respectively.
The three pairs of fundamental solutions given by (15.10.2), (15.10.4), and (15.10.6) can be transformed into 18 other solutions by means of (15.8.1), leading to a total of 24 solutions known as Kummer’s solutions.
The
connection formulas for the principal branches of
Kummer’s solutions are: