SUBROUTINE PLOT3D(ZV,SX,DX,SY,DY,MX,NX,MY,NY,IAX)
      DIMENSION ZV(NX,NY),ZU(100)
      LOGICAL READY
      CALL COM3D(ZV,SX,DX,SY,DY,MX,NX,MY,NY,IAX,B,C,F,HDY,XM,YM)
      E=ZV(MX,MY)+B
      ZU(MX)=E
      CALL POINT(C,E)
      IMX=MX+1
      DO 123 I=IMX,NX
      A=ZV(I,MY)+B
      ZU(I)=A
      D=C+(I-MX)*HDY
      CALL JOIN(D,A)
 123  CONTINUE
      K=NX+NY-MY
      INX=NX+1
      DO 125 I=INX,K
 125  ZU(I)=F
      IMY=MY+1
      DO 149 I=IMY,NY
      J=I-MY
      D=J*HDY
      A=B+D
      D=C+D
      F=A+ZV(MX,I)
      READY=F.GE.ZU(I)
      IF(.NOT.READY) GOTO 135
      ZU(I)=F
      CALL POINT(D,F)
 135  K=I+MX-MY
      IMX=MX+1
      DO 149 J=IMX,NX
      K=K+1
      F=A+ZV(J,I)
      IF(F.LT.ZU(K)) GOTO 147
      E=D+(J-MX)*HDY
      IF(.NOT.READY) GOTO 145
      CALL JOIN(E,F)
      ZU(K)=F
      GOTO 149
 145  READY=.TRUE.
      CALL POINT(E,F)
      GOTO 149
 147  READY=.FALSE.
 149  CONTINUE
      RETURN
      END