SUBROUTINE  VISPS (Z1,ZE,Z2,R1,R2,NR,P1,P2,NP,L,M)

C     [POLAR SEQUENCE]
C     L= 1  WESTERN VIEW,  L=-1  EASTERN VIEW
C     M= 1  SOUTHERN VIEW, M=-1  NORTHERN VIEW
C     [05-OCT-74]

      EXTERNAL    PLTCA
      DIMENSION   ZE(1),U(501),V(501)

      IX(J,I)=(I-1)*NR+J
      SC(Z)=0.167+ZS*(Z-Z1)

      N=L*M
      MM=1
      MK=501
      EL=FLOAT(L)
      EM=FLOAT(M)
      ZS=0.667/(Z2-Z1)
      DP=(P2-P1)/FLOAT(NP-1)
      DR=(R2-R1)/FLOAT(NR-1)

      I0=(NP+1-M*(NP-3))/2
      J0=((NR+1)-L*(NR-1))/2
      K0=((MK+1)*(1-N))/2
   10 K=K0
      I=MAX0(MIN0(I0,NP+1),0)
      J=J0
      P=P1+DP*FLOAT(I-1)
      R=R1+DR*FLOAT(J-1)
   20 IF ((I.GT.NP).OR.(I.LT.1)) GO TO 22
      K=MAX0(MIN0(K+N,MK),1)
      U(K)=0.5*(1.0+R*COS(P))
      V(K)=SC(ZE(IX(J,I)))+0.167*R*SIN(P)
   22 I=I-M
      P=P-EM*DP
      IF ((I.GT.NP).OR.(I.LT.1)) GO TO 30
      K=MAX0(MIN0(K+N,MK),1)
      U(K)=0.5*(1.0+R*COS(P))
      V(K)=SC(ZE(IX(J,I)))+0.167*R*SIN(P)
      J=J+L
      R=R+EL*DR
      IF ((J.LE.NR).AND.(J.GE.1)) GO TO 20
   30 IF (N.GT.0) CALL VISHO (U,V,K,MM,PLTCA)
      IF (N.LT.0) CALL VISHO (U(K),V(K),MK-K+1,MM,PLTCA)
      MM=-MM
      I0=I0+M
      IF ((I0.GE.0).AND.(I0.LE.NP+1)) GO TO 10
      J0=J0+L
      IF ((J0.GE.1).AND.(J0.LE.NR)) GO TO 10
      RETURN

      END