| Author(s): K.S. Kölbig | Library: MATHLIB |
| Submitter: | Submitted: 15.01.1988 |
| Language: Fortran | Revised: 15.03.1993 |
Function subprograms CWHITM and WWHITM compute the Whittacker function
for complex arguments z and complex indices
, where M(a,b,z) is Kummer's function (See Ref. 1).
The z-plane is cut along the negative real axis.
The double-precision version WWHITM is available only on computers which support a COMPLEX*16 Fortran data type.
Structure:
FUNCTION subprograms
User Entry Names: CWHITM, WWHITM
Files Referenced: Unit 6
External References:
| CLGAMA, | WLGAMA, | CCLBES, | WCLBES, | |
| MTLMTR, | ABEND |
Usage:
In any arithmetic expression,
CWHITM(Z,KA,MU) or WWHITM(Z,KA,MU) has the
value 
and 
.
CWHITM is of type COMPLEX, WWHITM is of type
COMPLEX*16, and Z, KA and
MU have the same type as the function name.
Method:
For 
or 
equal to a
negative
integer, 
reduces to a polynomial in z. For other
values, a regular Coulomb wave function 
is computed by using subprogram CCLBES (C309)
in conjunction with functional relations.
Restrictions:
;
Re 
if Im z=0.
Accuracy:
CWHITM (except on CDC and Cray computers) has full single-precision accuracy. For most values of the arguments, WWHITM (and CWHITM on CDC and Cray computers) has an accuracy of approximately two to three decimal digits less than the machine precision.
Error handling:
Error C328.1: 
with 
and
.
Error C328.2: 
.
In both cases, the function value is set equal to zero,
and a message is written on
Unit 6, unless subroutine MTLSET (N002) has been called.
An error message is also written on Unit 6 if the internal call to
CCLBES or WCLBES returns 
(see Short write-up for CCLBES (C309)).
References:
