SUBROUTINE  PLTHP (NR,NT)

C     [HYPERBOLIC POLAR]
C     NR   NUMBER OF CIRCLES OF CONSTANT RADIUS
C     NT   NUMBER OF RADII OF CONSTANT ANGLE
C     POLAR COORDINATE GRID WITH RADIAL HYPERBOLIC TANGENT DISTORTION.
C     [14-MAR-73]

      DATA        HX,HY/4.50,3.25/
      DATA        RR,UU/3.25,3.00/

      CALL PLTBO
      CALL PLTRI (-HX,-HY,1)
      CALL PLTRI ( HX, HY,2)
      DT=6.28318/FLOAT(NT)

      IF (NR.LT.1) GO TO 11
      DO 10 I=1,NR
   10 CALL PLTCI (0.0,0.0,RR*TANH(FLOAT(I)/UU))
   11 CALL PLTCI (0.0,0.0,RR)

      T=0.0
      SS=(0.25*RR)/UU
      DO 20 I=1,NT,2
      CALL PLTRI (RR*COS(T),RR*SIN(T),3)
      CALL PLTRI (SS*COS(T),SS*SIN(T),4)
      T=T+DT
      CALL PLTRI (SS*COS(T),SS*SIN(T),3)
      CALL PLTRI (RR*COS(T),RR*SIN(T),4)
   20 T=T+DT
      RETURN

      END