C341: Modified Bessel Functions K of Certain Order

Author(s): K.S. Kölbig	Library: MATHLIB
Submitter:	Submitted: 15.10.1994
Language: Fortran	Revised:

Subroutine subprograms BSKA and DBSKA calculate the sequence of modified Bessel functions

for real argument x>0 and a chosen .
On CDC and Cray computers, the double-precision versions DBSKA and DEBKA are not available.

Structure:

SUBROUTINE subprograms
User Entry Names: BSKA, EBSKA, DBSKA,DEBKA
Files Referenced: Unit 6
External References:

BESK0, BESK1, EBESK0, EBESK1,

DBESK0, DBESK1, DEBSK0, DEBSK1,

BSKR4, EBSKR4, DBSKR4, DEBKR4,

BSKR3, EBSKR3, DBSKR3, DEBKR3, MTLMTR, ABEND

Usage:

Single-precision version:
CALL BSKA(X,IA,JA,NL,B) or CALL EBSKA(X,IA,JA,NL,B)

X

(REAL) Argument x.

IA,JA

(INTEGER) Numerator i and denominator j of a=i/j. Only the pairs

          (IA,JA) = (0,1), (1,2), (1,3), (1,4), (2,3), (3,4)

are permitted. For example, and corresponds to a=2/3.

NL

(INTEGER) Specifies the order of the last Bessel function in the computed sequence.

B

(REAL) One-dimensional array with dimension (0:d) where .
On exit, , , contains for BSKA, for EBSKA, respectively.

Double-precision version:
CALL DBSKA(X,IA,JA,NL,B) or CALL DEBKA(X,IA,JA,NL,B)
where X and B are of type DOUBLE PRECISION.

Method:

The well-known recurrence relation for modified Bessel functions is used.

Restrictions:

, . Only the pairs (IA,JA) given above are permitted.

Error handling:

Error C341.1: .
Error C341.2: Pair (IA,JA) not permitted.
Error C341.3: .
In all cases, a message is written on Unit 6, unless subroutine MTLSET (N002) has been called. The initial contents of array B is left unchanged.