Program c05avfe

!     C05AVF Example Program Text

!     Mark 27.2 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use nag_library, Only: c05avf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: boundl, boundu, fx, h, x, y
      Integer                          :: ifail, ind
!     .. Local Arrays ..
      Real (Kind=nag_wp)               :: c(11)
!     .. Executable Statements ..
      Write (nout,*) 'C05AVF Example Program Results'

      Write (nout,*)

      x = 3.0E0_nag_wp
      h = 0.1E0_nag_wp
      boundl = 0.0E0_nag_wp
      boundu = 4.0E0_nag_wp
      ind = 1
      ifail = -1

revcomm: Do

        Call c05avf(x,fx,h,boundl,boundu,y,c,ind,ifail)

        If (ind==0) Then
          Exit revcomm
        End If

        fx = x*x - 3.0E0_nag_wp*x + 2.0E0_nag_wp
      End Do revcomm

      If (ifail==0) Then
        Write (nout,*) 'Interval containing root is [X,Y], where'
        Write (nout,99999) 'X =', x, '   Y =', y
        Write (nout,*) 'Values of f at X and Y are'
        Write (nout,99999) 'f(X) =', fx, '   f(Y) =', c(1)
      End If

99999 Format (1X,2(A,F12.4))
    End Program c05avfe