!   D01FCF Example Program Text
!   Mark 28.3 Release. NAG Copyright 2022.

    Module d01fcfe_mod

!     D01FCF 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       :: ndim = 4, nout = 6
      Integer, Parameter, Public       :: maxpts = 1000*ndim
      Integer, Parameter, Public       :: lenwrk = (ndim+2)*(1+maxpts/(2**ndim &
                                          +2*ndim*ndim+2*ndim+1))
    Contains
      Function f(ndim,z)

!       .. Function Return Value ..
        Real (Kind=nag_wp)             :: f
!       .. Scalar Arguments ..
        Integer, Intent (In)           :: ndim
!       .. Array Arguments ..
        Real (Kind=nag_wp), Intent (In) :: z(ndim)
!       .. Intrinsic Procedures ..
        Intrinsic                      :: exp
!       .. Executable Statements ..
        f = 4.0E0_nag_wp*z(1)*z(3)*z(3)*exp(2.0E0_nag_wp*z(1)*z(3))/           &
          (1.0E0_nag_wp+z(2)+z(4))**2

        Return

      End Function f
    End Module d01fcfe_mod
    Program d01fcfe

!     D01FCF Example Main Program

!     .. Use Statements ..
      Use d01fcfe_mod, Only: f, lenwrk, maxpts, ndim, nout
      Use nag_library, Only: d01fcf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: acc, eps, finval
      Integer                          :: ifail, minpts
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: a(:), b(:), wrkstr(:)
!     .. Executable Statements ..
      Write (nout,*) 'D01FCF Example Program Results'

      Allocate (a(ndim),b(ndim),wrkstr(lenwrk))

      a(1:ndim) = 0.0E0_nag_wp
      b(1:ndim) = 1.0E0_nag_wp
      eps = 0.0001E0_nag_wp
      minpts = 0

      ifail = -1
      Call d01fcf(ndim,a,b,minpts,maxpts,f,eps,acc,lenwrk,wrkstr,finval,ifail)

      Select Case (ifail)
      Case (0,2:)
        Write (nout,*)
        Write (nout,99999) 'Requested accuracy = ', eps
        Write (nout,99998) 'Estimated value    = ', finval
        Write (nout,99999) 'Estimated accuracy = ', acc
      End Select

99999 Format (1X,A,E12.2)
99998 Format (1X,A,F12.4)
    End Program d01fcfe