PROGRAM MAIN
      IMPLICIT REAL(A-H,O-Z), INTEGER(I-N)
      PARAMETER (N = 2, LWA = 2*N + (6*N + 1)*2**N)
      DIMENSION X0(N), H(N), AS(N), VAS(N), WA(LWA)
      EXTERNAL FNC
      COMMON / BLK1 / NFCALL
c
c  Set the values of DELTA, EPSILO, and ICO.
c
      DATA DELTA, EPSILO, ICON / 0.625E-1, 1.0E-6, 1 /
c
c  Set the starting values.
c
      DATA X0 / 2* - 2000.0E0 /
      DATA H / 2*4000.0E0 /
      PRINT 9999, ( X0(J), H(J), J = 1, N )
c
c  Call the interface subroutine intsub().
c
      NFCALL = 0
      CALL INTSUB ( FNC, N, X0, H, DELTA, EPSILO, ICON, INF1,
     &  AS, VAS, INF2, WA, LWA )

      IF ( INF1 .EQ. 0 ) THEN
        PRINT 9998
      ELSE IF ( INF1 .EQ. 2 .AND. ICON .NE. 1 ) THEN
        PRINT 9997, N
      ELSE
        PRINT 9996, DELTA, EPSILO, (AS(J), VAS(J), J = 1, N)
      ENDIF

      NFCALL = INT( REAL( NFCALL ) / REAL( N ) )
      PRINT 9995, INF1, INF2, NFCALL
      STOP
9999  FORMAT (//2X, 'INITIAL GUESS :', 17X, 'STEPSIZES :'//
     &  2( F16.7, 16X, F16.7 / ) )
9998  FORMAT(//5X, '*** IMPROPER INPUT PARAMETERS***'//)
9997  FORMAT(//5X, '*** THE CHARACTERISTIC', I2,
     &  '-POLYHEDRON HAS NOT BEEN COMPLETED***'//)
9996  FORMAT(//2X, 'DELTA = ', F20.18 //2X, 'EPSILO = ', F20.18
     &  ////2X, 'FINAL APPROXIMATE SOLUTION:', 5X,
     &  'VERIFICATION OF THE SOLUTION:' //9(F24.18,9X,
     &  F24.18/ ))
9995  FORMAT (//2X, 'EXIT PARAMETERS: INF1 =', i1,1X, ', INF2 ='
     &  i1//2X, 'NUMBER OF FUNCTION CALLS : NFCALL = ',
     &  i4 )
      END
      REAL FUNCTION FNC( X, IFLAG )
      INTEGER IFLAG, NFCALL
      REAL X(2)
      COMMON / BLK1 / NFCALL
      NFCALL = NFCALL + 1
      if ( iflag == 1 ) then
        FNC = X(1)** 2 - 4.0E0*X(2)
      else
        FNC = X(2)** 2 - 2.0E0*X(1) + 4.0E0*X(2)
      end if
      RETURN
      END