!   E04AB_P0W_F Example Program Text
!   Mark 27.3 Release. NAG Copyright 2021.
    Module e04ab_p0w_fe_mod

!     E04AB_P0W_F Example Program Module:
!            Parameters and User-defined Routines

!     .. Use Statements ..
      Use iso_c_binding, Only: c_ptr
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Accessibility Statements ..
      Private
      Public                           :: funct
!     .. Parameters ..
      Integer, Parameter, Public       :: nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp), Public, Save :: t
    Contains
      Subroutine funct(ad_handle,xc,fc,iuser,ruser)
!       Routine to evaluate F(x) at any point in (A, B)

!       .. Scalar Arguments ..
        Type (c_ptr), Intent (Inout)   :: ad_handle
        Real (Kind=nag_wp), Intent (Out) :: fc
        Real (Kind=nag_wp), Intent (In) :: xc
!       .. Array Arguments ..
        Real (Kind=nag_wp), Intent (Inout) :: ruser(*)
        Integer, Intent (Inout)        :: iuser(*)
!       .. Intrinsic Procedures ..
        Intrinsic                      :: sin
!       .. Executable Statements ..
        fc = sin(t*xc)/(xc)

        Return

      End Subroutine funct
    End Module e04ab_p0w_fe_mod
    Program e04ab_p0w_fe

!     E04AB_P0W_F Example Main Program

!     .. Use Statements ..
      Use e04ab_p0w_fe_mod, Only: funct, nout, t
      Use iso_c_binding, Only: c_ptr
      Use nagad_library, Only: e04ab_p0w_f
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Type (c_ptr)                     :: ad_handle
      Real (Kind=nag_wp)               :: a, b, e1, e2, f, x
      Integer                          :: ifail, maxcal
!     .. Local Arrays ..
      Real (Kind=nag_wp)               :: ruser(1)
      Integer                          :: iuser(1)
!     .. Executable Statements ..
      Write (nout,*) 'E04AB_P0W_F Example Program Results'

      e1 = 0.0_nag_wp
      e2 = 0.0_nag_wp

!     The minimum is known to lie in the range (3.5, 5.0)
      a = 3.5_nag_wp
      b = 5.0_nag_wp

      t = 1.0_nag_wp
!     Allow 30 calls of FUNCT

      maxcal = 30

      ifail = -1
      Call e04ab_p0w_f(ad_handle,funct,e1,e2,a,b,maxcal,x,f,iuser,ruser,ifail)

      Select Case (ifail)
      Case (0,2)
        Write (nout,*)
        Write (nout,99999) 'The minimum lies in the interval', a, ' to', b
        Write (nout,99999) 'Its estimated position is       ', x, ','
        Write (nout,99998) 'where the function value is     ', f
        Write (nout,99997) maxcal, 'function evaluations were required'
      Case (:-1)
        Write (nout,99996) 'Routine e04ab_p0w_f failed with ifail = ', ifail
      End Select


99999 Format (1X,A,F11.8,A,F11.8)
99998 Format (1X,A,F7.4)
99997 Format (1X,I2,1X,A)
99996 Format (/,1X,A,I0)
    End Program e04ab_p0w_fe