var/convertor/wave2grid_kma/GAUSS.inc

   1       SUBROUTINE GAUSS(A,W,K)
   2 C
   3 C  A; COSINE OF COLATITUDE
   4 C  W; GAUSSIAN WEIGHT
   5 C  K; ORDER OF LEGENDRE FUNCTIONS
   6 C
   7       IMPLICIT REAL*8(A-H,O-Z)
   8 C
   9       DIMENSION A(K),W(K)
  10 C
  11       ESP=1.E-14
  12       C=(1.E0-(2.E0/pi)**2)*0.25E0
  13       FK=K
  14       KK=K/2
  15       CALL BSSLZ1(A,KK)
  16       DO 30 IS=1,KK
  17       XZ=COS(A(IS)/SQRT((FK+0.5E0)**2+C))
  18       ITER=0
  19    10 PKM2=1.0
  20       PKM1=XZ
  21       ITER=ITER+1
  22       IF(ITER.GT.10) GO TO 70
  23       DO 20 N=2,K
  24       FN=N
  25       PK=((2.E0*FN-1.E0)*XZ*PKM1-(FN-1.0)*PKM2)/FN
  26       PKM2=PKM1
  27    20 PKM1=PK
  28       PKM1=PKM2
  29       PKMRK=(FK*(PKM1-XZ*PK))/(1.E0-XZ**2)
  30       SP=PK/PKMRK
  31       XZ=XZ-SP
  32       AVSP=ABS(SP)
  33       IF(AVSP.GT.ESP) GO TO 10
  34       A(IS)=XZ
  35       W(IS)=(2.E0*(1.E0-XZ**2))/(FK*PKM1)**2
  36    30 CONTINUE
  37       IF(K.EQ.KK*2) GO TO 50
  38       A(KK+1)=0.E0
  39       PK=2.E0/FK**2
  40       DO 40 N=2,K,2
  41       FN=N
  42    40 PK=PK*FN**2/(FN-1.E0)**2
  43       W(KK+1)=PK
  44    50 CONTINUE
  45       DO 60 N=1,KK
  46       L=K+1-N
  47       A(L)=-A(N)
  48    60 W(L)=W(N)
  49       RETURN
  50    70 WRITE(96,6000)
  51  6000 FORMAT(//5X,14HERROR IN GAUAW//)
  52 C
  53       STOP
  54       END SUBROUTINE GAUSS