ASYJY(3)

SYNOPSIS
SUBROUTINE ASYJY (FUNJY, X, FNU, FLGJY, IN, Y, WK, IFLW)

NAME
asyjy - Subsidiary to BESJ and BESY

LIBRARY
SLATEC

TYPE
SINGLE PRECISION (ASYJY-S, DASYJY-D)

AUTHOR
Amos, D. E., (SNLA)

DESCRIPTION
ASYJY computes Bessel functions J and Y for arguments X.GT.0.0 and orders FNU.GE.35.0 on FLGJY = 1 and FLGJY = -1 respectively INPUT FUNJY - external function JAIRY or YAIRY X - argument, X.GT.0.0E0 FNU - order of the first Bessel function FLGJY - selection flag FLGJY = 1.0E0 gives the J function FLGJY = -1.0E0 gives the Y function IN - number of functions desired, IN = 1 or 2 OUTPUT Y - a vector whose first in components contain the sequence IFLW - a flag indicating underflow or overflow return variables for BESJ only WK(1) = 1 - (X/FNU)**2 = W**2 WK(2) = SQRT(ABS(WK(1))) WK(3) = ABS(WK(2) - ATAN(WK(2))) or ABS(LN((1 + WK(2))/(X/FNU)) - WK(2)) = ABS((2/3)*ZETA**(3/2)) WK(4) = FNU*WK(3) WK(5) = (1.5*WK(3)*FNU)**(1/3) = SQRT(ZETA)*FNU**(1/3) WK(6) = SIGN(1.,W**2)*WK(5)**2 = SIGN(1.,W**2)*ZETA*FNU**(2/3) WK(7) = FNU**(1/3) Abstract ASYJY implements the uniform asymptotic expansion of the J and Y Bessel functions for FNU.GE.35 and real X.GT.0.0E0. 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 FLGJY = 1 or -1. On FLGJY = 1 the AIRY functions AI(X) and DAI(X) are supplied by the external function JAIRY, and on FLGJY = -1 the AIRY functions BI(X) and DBI(X) are supplied by the external function YAIRY.

SEE ALSO
BESJ, BESY

ROUTINES CALLED
I1MACH, R1MACH

REVISION HISTORY (YYMMDD)
750101 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
891009 Removed unreferenced variable. (WRB)
891214 Prologue converted to Version 4.0 format. (BAB)
900328 Added TYPE section. (WRB)
910408 Updated the AUTHOR section. (WRB)