PROGRAM PGEX11
C-----------------------------------------------------------------------
C Test routine for PGPLOT: draws a skeletal dodecahedron.
C-----------------------------------------------------------------------
      INTEGER NVERT, PGOPEN
      REAL T, T1, T2, T3
      PARAMETER (NVERT=20)
      PARAMETER (T=1.618)
      PARAMETER (T1=1.0+T)
      PARAMETER (T2=-1.0*T)
      PARAMETER (T3=-1.0*T1)
      INTEGER I, J, K
      REAL VERT(3,NVERT), R, ZZ
      REAL X(2),Y(2)
C
C Cartesian coordinates of the 20 vertices.
C
      DATA VERT/ T, T, T,       T, T,T2,
     3           T,T2, T,       T,T2,T2,
     5          T2, T, T,      T2, T,T2,
     7          T2,T2, T,      T2,T2,T2,
     9          T1,1.0,0.0,    T1,-1.0,0.0,
     B          T3,1.0,0.0,    T3,-1.0,0.0,
     D          0.0,T1,1.0,    0.0,T1,-1.0,
     F          0.0,T3,1.0,    0.0,T3,-1.0,
     H          1.0,0.0,T1,    -1.0,0.0,T1,
     J          1.0,0.0,T3,   -1.0,0.0,T3 /
C
C Call PGOPEN to initiate PGPLOT and open the output device; PGOPEN
C will prompt the user to supply the device name and type. Always
C check the return code from PGOPEN.
C
      IF (PGOPEN('?') .LE. 0) STOP
C
C Initialize the plot (no labels).
C
      CALL PGBBUF
      CALL PGSAVE
      CALL PGENV(-4.,4.,-4.,4.,1,-2)
      CALL PGSCI(2)
      CALL PGSLS(1)
      CALL PGSLW(1)
C
C Write a heading.
C
      CALL PGLAB(' ',' ','PGPLOT Example 11:  Dodecahedron')
C
C Mark the vertices.
C
      DO 2 I=1,NVERT
          ZZ = VERT(3,I)
          CALL PGPT1(VERT(1,I)+0.2*ZZ,VERT(2,I)+0.3*ZZ,9)
    2 CONTINUE
C
C Draw the edges - test all vertex pairs to find the edges of the 
C correct length.
C
      CALL PGSLW(3)
      DO 20 I=2,NVERT
          DO 10 J=1,I-1
              R = 0.
              DO 5 K=1,3
                  R = R + (VERT(K,I)-VERT(K,J))**2
    5         CONTINUE
              R = SQRT(R)
              IF(ABS(R-2.0).GT.0.1) GOTO 10
              ZZ = VERT(3,I)
              X(1) = VERT(1,I)+0.2*ZZ
              Y(1) = VERT(2,I)+0.3*ZZ
              ZZ = VERT(3,J)
              X(2) = VERT(1,J)+0.2*ZZ
              Y(2) = VERT(2,J)+0.3*ZZ
              CALL PGLINE(2,X,Y)
   10     CONTINUE
   20 CONTINUE
      CALL PGUNSA
      CALL PGEBUF
C
C Finally, call PGCLOS to terminate things properly.
C
      CALL PGCLOS
C
      END