DASYJY(3)

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

NAME
dasyjy - Subsidiary to DBESJ and DBESY

LIBRARY
SLATEC

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

AUTHOR
Amos, D. E., (SNLA)

DESCRIPTION
DASYJY 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 subroutine JAIRY or YAIRY X - Argument, X.GT.0.0D0 FNU - Order of the first Bessel function FLGJY - Selection flag FLGJY = 1.0D0 gives the J function FLGJY = -1.0D0 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 **** A Double Precision Routine **** DASYJY implements the uniform asymptotic expansion of the J and Y 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 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
DBESJ, DBESY

ROUTINES CALLED
D1MACH, I1MACH

REVISION HISTORY (YYMMDD)
750101 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890911 Removed unnecessary intrinsics. (WRB)
891004 Correction computation of ELIM. (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)