SUBROUTINE  VISSS (FU,J1,J2,NP,I1,I2,NT,L,M,S,B,O,PR,PL)

C     [SPHERICAL SEQUENCE]
C     FU(NP,NT)  ARRAY OF FUNCTION VALUES
C     (J1,J2)    INTERVAL OF PHI INDICES TO BE GRAPHED
C     (I1,I2)    INTERVAL OF THETA INDICES TO BE GRAPHED
C     L= 1  WESTERN VIEW,  L=-1  EASTERN VIEW
C     M= 1  SOUTHERN VIEW, M=-1  NORTHERN VIEW
C     B= (ATAN2 CUT LINE DOES NOT FALL IN QUADRANT BEING GRAPHED)
C     O(3,3)     ORTHOGONAL ROTATION MATRIX
C     PR         PROJECTION SUBROUTINE
C     PL         PEN MOVEMENT SUBROUTINE
C     [22-NOV-74]

      EXTERNAL    PL
      LOGICAL*1     B
      DIMENSION   FU(1),O(3,3)
      DIMENSION   AZ(501),RA(501),OR(501)
      DATA        MK/501/

      TAN(X)=SIN(X)/COS(X)
      IX(J,I)=(I-1)*NP+MOD(NP+J-1,NP)+1
      ZP(X1,Y1,X2,Y2)=X1-Y1*((X2-X1)/(Y2-Y1))
      WH(T,P)=S*SIGN(1.0,1.57079-T)*(TAN(T)-TN*COS(P-PH))

      N=L*M
      NN=1
      EL=FLOAT(L)
      EM=FLOAT(M)
      DP=6.28/FLOAT(NP)
      DT=3.14/FLOAT(NT)
      CALL VISNP (PH,TH,JP,IT,NP,NT,O)
      TN=TAN(TH)

      I0=((I1+I2)+M*(I1-I2))/2+M
      J0=((J1+J2)+L*(J1-J2))/2
      K0=((MK+1)*(1-N))/2
   10 K=K0
      I=MAX0(MIN0(I0,I2+1),I1-1)
      J=J0
      T=TH+DT*FLOAT(I-IT)
      P=PH+DP*FLOAT(J-JP)
   20 IF ((I.GT.I2).OR.(I.LT.I1)) GO TO 22
      K=MAX0(MIN0(K+N,MK),1)
      CALL PR (RA(K),AZ(K),FU(IX(J,I)),T,P,O)
      OR(K)=WH(T,P)
   22 I=I-M
      T=T-EM*DT
      IF ((I.GT.I2).OR.(I.LT.I1)) GO TO 30
      K=MAX0(MIN0(K+N,MK),1)
      CALL PR (RA(K),AZ(K),FU(IX(J,I)),T,P,O)
      OR(K)=WH(T,P)
      J=J+L
      P=P+EL*DP
      IF ((J.LE.J2).AND.(J.GE.J1)) GO TO 20

   30 IF (N.GT.0) GO TO 32
      M1=MK-K+1
      DO 31 MM=1,M1
      AZ(MM)=AZ(K+MM-1)
      RA(MM)=RA(K+MM-1)
   31 OR(MM)=OR(K+MM-1)
      K=M1
   32 IF (K.LE.1) GO TO 50
      IF (B) GO TO 36
      DO 35 MM=1,K
   35 IF (AZ(MM).LT.0.0) AZ(MM)=AZ(MM)+1.0
   36 IF (AZ(1).LE.AZ(K)) GO TO 38
      DO 37 MM=1,K
      T1=AZ(MM)
      T2=RA(MM)
      T3=OR(MM)
      AZ(MM)=AZ(K-MM+1)
      RA(MM)=RA(K-MM+1)
      OR(MM)=OR(K-MM+1)
      AZ(K-MM+1)=T1
      RA(K-MM+1)=T2
   37 OR(K-MM+1)=T3
   38 K1=0
   40 K1=K1+1
      IF (K1.GE.K) GO TO 50
      IF (OR(K1).GT.0.0) GO TO 40
      K2=K1
      IF (K1.LE.1) GO TO 41
      K1=K1-1
      AZ(K1)=ZP(AZ(K1),OR(K1),AZ(K1+1),OR(K1+1))
      RA(K1)=ZP(RA(K1),OR(K1),RA(K1+1),OR(K1+1))
   41 IF (K2.GT.K) GO TO 43
      IF (OR(K2).GT.0.0) GO TO 42
      K2=K2+1
      GO TO 41
   42 IF (K2.GT.K) GO TO 43
      AZ(K2)=ZP(AZ(K2),OR(K2),AZ(K2-1),OR(K2-1))
      RA(K2)=ZP(RA(K2),OR(K2),RA(K2-1),OR(K2-1))
      K2=K2+1
   43 IF (K2-K1.LT.2) GO TO 44
      IF (AZ(K1).GE.AZ(K1+1)) AZ(K1)=AZ(K1+1)-0.0025
      IF (AZ(K2-1).LE.AZ(K2-2)) AZ(K2-1)=AZ(K2-2)+0.0025
   44 IF (K2-K1.GT.1) CALL VISHO (AZ(K1),RA(K1),K2-K1,NN,PL)
      K1=K2
      GO TO 40

   50 NN=-NN
      I0=I0+M
      IF ((I0.GE.I1-1).AND.(I0.LE.I2+1)) GO TO 10
      J0=J0+L
      IF ((J0.GE.J1).AND.(J0.LE.J2)) GO TO 10
      RETURN

      END