SUBROUTINE  PLTTV (Z1,ZE,Z2,N,M)

C     [TRIANGULAR VIEW]
C     PROGRAM TO PRODUCE A PERSPECTIVE DRAWING OF A FUNCTION DEFINED
C     OVER THE UNIT TRIANGLE IN TERMS OF HOMOGENEOUS COORDINATES. THE
C     FUNCTION VALUES OCCUPY THE UPPER TRIANGULAR PORTION OF THE SQUARE
C     MATRIX ZE(M,M), OF WHICH ONLY THE FRAGMENT ZE(N,N) IS TO BE DRAWN.
C     IN GENERATING THE DRAWING, THE VALUES IN ZE WILL BE SCALED TO THE
C     RANGE Z1,Z2.
C     [22-NOV-74]

      DIMENSION   ZE(1)

      CALL PLTFR
      CALL VISNH
      CALL VISTS (Z1,ZE,Z2,N,M)
      CALL PLTEJ
      RETURN

      END