§28.20 Definitions and Basic Properties
Contents
- §28.20(i) Modified Mathieu’s Equation
- §28.20(ii) Solutions
,
,
,
, 
- §28.20(iii) Solutions

- §28.20(iv) Radial Mathieu Functions
,

- §28.20(v) Solutions
,
,
, 
- §28.20(vi) Wronskians
- §28.20(vii) Shift of Variable
§28.20(i) Modified Mathieu’s Equation
When
is replaced by
, (28.2.1) becomes the
modified Mathieu’s equation:
28.20.1
with its algebraic form
28.20.2
.
§28.20(ii) Solutions
,
,
,
,
28.20.3
,
28.20.4
,
28.20.5
28.20.6
,
28.20.7
.
§28.20(iii) Solutions
Assume first that
is real,
is positive, and
;
see §28.12(i). Write
28.20.8
Then from §2.7(ii) it is seen that equation (28.20.2)
has independent and unique solutions that are asymptotic to
as
in the
respective sectors
,
being an arbitrary small positive constant. It follows that
(28.20.1) has independent and unique solutions
,
such that
28.20.9
as
with
, and
28.20.10
as
with
. See §10.2(ii) for
the notation. In addition, there are unique solutions
,
that are real when
is real and have the properties
28.20.11
28.20.12
as
with
.
For other values of
,
and
the functions
,
are determined by analytic
continuation. Furthermore,
28.20.13
28.20.14
§28.20(iv) Radial Mathieu Functions
,
For
,
28.20.15
,
28.20.16
.
§28.20(v) Solutions
,
,
,
28.20.17
28.20.18
28.20.19
28.20.20
§28.20(vi) Wronskians
28.20.21

