DASYIK(3)

SYNOPSIS
SUBROUTINE DASYIK (X, FNU, KODE, FLGIK, RA, ARG, IN, Y)

NAME
dasyik - Subsidiary to DBESI and DBESK

LIBRARY
SLATEC

TYPE
DOUBLE PRECISION (ASYIK-S, DASYIK-D)

AUTHOR
Amos, D. E., (SNLA)

DESCRIPTION
DASYIK computes Bessel functions I and K for arguments X.GT.0.0 and orders FNU.GE.35 on FLGIK = 1 and FLGIK = -1 respectively. INPUT X - Argument, X.GT.0.0D0 FNU - Order of first Bessel function KODE - A parameter to indicate the scaling option KODE=1 returns Y(I)= I/SUB(FNU+I-1)/(X), I=1,IN or Y(I)= K/SUB(FNU+I-1)/(X), I=1,IN on FLGIK = 1.0D0 or FLGIK = -1.0D0 KODE=2 returns Y(I)=EXP(-X)*I/SUB(FNU+I-1)/(X), I=1,IN or Y(I)=EXP( X)*K/SUB(FNU+I-1)/(X), I=1,IN on FLGIK = 1.0D0 or FLGIK = -1.0D0 FLGIK - Selection parameter for I or K FUNCTION FLGIK = 1.0D0 gives the I function FLGIK = -1.0D0 gives the K function RA - SQRT(1.+Z*Z), Z=X/FNU ARG - Argument of the leading exponential IN - Number of functions desired, IN=1 or 2 OUTPUT Y - A vector whose first IN components contain the sequence Abstract **** A double precision routine **** DASYIK implements the uniform asymptotic expansion of the I and K Bessel functions for FNU.GE.35 and real X.GT.0.0D0. The forms are identical except for a change in sign of some of the terms. This change in sign is accomplished by means of the FLAG FLGIK = 1 or -1.

SEE ALSO
DBESI, DBESK

ROUTINES CALLED
D1MACH

REVISION HISTORY (YYMMDD)
750101 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890911 Removed unnecessary intrinsics. (WRB)
891214 Prologue converted to Version 4.0 format. (BAB)
900328 Added TYPE section. (WRB)
910408 Updated the AUTHOR section. (WRB)