!   D01RGF Example Program Text
!   Mark 30.1 Release. NAG Copyright 2024.

    Module d01rgfe_mod

!     D01ATF Example Program Module:
!            Parameters and User-defined Routines

!     .. Use Statements ..
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Accessibility Statements ..
      Private
      Public                           :: f
!     .. Parameters ..
      Integer, Parameter, Public       :: nout = 6
    Contains
      Subroutine f(x,nx,fv,iflag,iuser,ruser)

!       .. Scalar Arguments ..
        Integer, Intent (Inout)        :: iflag
        Integer, Intent (In)           :: nx
!       .. Array Arguments ..
        Real (Kind=nag_wp), Intent (Out) :: fv(nx)
        Real (Kind=nag_wp), Intent (Inout) :: ruser(*)
        Real (Kind=nag_wp), Intent (In) :: x(nx)
        Integer, Intent (Inout)        :: iuser(*)
!       .. Intrinsic Procedures ..
        Intrinsic                      :: log, sin
!       .. Executable Statements ..
        fv = sin(x)/x*log(10.0_nag_wp*(1.0_nag_wp-x))
        Return
      End Subroutine f
    End Module d01rgfe_mod
    Program d01rgfe

!     D01RGF Example Main Program

!     .. Use Statements ..
      Use d01rgfe_mod, Only: f, nout
      Use nag_library, Only: d01rgf, nag_wp, x07caf, x07cbf
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: a, b, dinest, epsabs, epsrel, errest
      Integer                          :: ifail, nevals
!     .. Local Arrays ..
      Real (Kind=nag_wp)               :: ruser(1)
      Integer                          :: exmode(3), exmode_old(3), iuser(1)
!     .. Executable Statements ..
      Write (nout,*) 'D01RGF Example Program Results'

!     The example function can raise various exceptions - it contains
!     a division by zero and a log singularity - although its integral
!     is well behaved.

!     Save the original halting mode
      Call x07caf(exmode_old)

!     Turn exception halting mode off for the three common exceptions
!     overflow, division-by-zero, and invalid operation.
      exmode = (/0,0,0/)
      Call x07cbf(exmode)

      epsabs = 0.0_nag_wp
      epsrel = 1.0E-04_nag_wp
      a = -1.0_nag_wp
      b = 1.0_nag_wp

!     Evaluate the integral
      ifail = -1
      Call d01rgf(a,b,f,epsabs,epsrel,dinest,errest,nevals,iuser,ruser,ifail)

      Write (nout,*)
      Write (nout,99999) 'A     ', 'lower limit of integration', a
      Write (nout,99999) 'B     ', 'upper limit of integration', b
      Write (nout,99998) 'EPSABS', 'absolute accuracy requested', epsabs
      Write (nout,99998) 'EPSREL', 'relative accuracy requested', epsrel
      Write (nout,*)
      If (ifail>=0) Then
        Write (nout,99997) 'DINEST', 'approximation to the integral', dinest
        Write (nout,99998) 'ERREST', 'estimate of the absolute error', errest
        Write (nout,99996) 'NEVALS', 'number of function evaluations', nevals
      End If

!     Restore the original halting mode
      Call x07cbf(exmode_old)

99999 Format (1X,A6,' - ',A30,' = ',F10.4)
99998 Format (1X,A6,' - ',A30,' = ',E10.2)
99997 Format (1X,A6,' - ',A30,' = ',F10.5)
99996 Format (1X,A6,' - ',A30,' = ',I10)
    End Program d01rgfe