!!!!!!!!!!!!!!!!!!!!!!!!!!! Program 5.5 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! !
! Please Note: !
! !
! (1) This computer program is written by Tao Pang in conjunction with !
! his book, "An Introduction to Computational Physics," published !
! by Cambridge University Press in 1997. !
! !
! (2) No warranties, express or implied, are made for this program. !
! !
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
SUBROUTINE BSSL (BJ,BY,N,X)
!
! Subroutine to generate J_n(x) and Y_n(x) with given x and
! up to N=NMAX-NTEL.
!
INTEGER, PARAMETER :: NMAX=30,NTEL=5
INTEGER, INTENT (IN) :: N
INTEGER :: I,J,K
REAL, INTENT (IN) :: X
REAL :: PI,GAMMA,SUM,SUM1
REAL, INTENT (OUT), DIMENSION (0:N) :: BJ,BY
REAL, DIMENSION (0:NMAX) :: B1
!
PI = 4.0*ATAN(1.0)
GAMMA = 0.5772156649
!
B1(NMAX) = 0.0
B1(NMAX-1) = 1.0
!
! Generating J_n(x)
!
SUM = 0.0
DO I = NMAX-1, 1, -1
B1(I-1) = 2*I*B1(I)/X-B1(I+1)
IF (MOD(I,2).EQ.0) SUM = SUM+2.0*B1(I)
END DO
SUM = SUM+B1(0)
!
DO I = 0, N
BJ(I) = B1(I)/SUM
END DO
!
! Generating Y_n(x) starts here
!
SUM1 = 0.0
DO K = 1, NMAX/2
SUM1 = SUM1+(-1)**K*B1(2*K)/K
END DO
!
SUM1 = -4.0*SUM1/(PI*SUM)
BY(0) = 2.0*(ALOG(X/2.0)+GAMMA)*BJ(0)/PI+SUM1
BY(1) = (BJ(1)*BY(0)-2.0/(PI*X))/BJ(0)
DO I = 1, N-1
BY(I+1) = 2*I*BY(I)/X-BY(I-1)
END DO
END SUBROUTINE BSSL