```    Program e01be_a1w_fe

!     E01BE_A1W_F Example Program Text
!     Mark 26.2 Release. NAG Copyright 2017.

!     .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: e01be_a1w_f, e01bg_a1w_f,                       &
x10aa_a1w_f, x10ab_a1w_f, Assignment (=)
Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Type (c_ptr)                     :: ad_handle
Real (Kind=nag_wp)               :: fr, xr
Integer                          :: i, ifail, m, n, r
!     .. Local Arrays ..
Type (nagad_a1w_w_rtype), Allocatable :: d(:), f(:), pd(:), pf(:),       &
px(:), x(:)
Real (Kind=nag_wp), Allocatable  :: df(:), dx(:)
!     .. Executable Statements ..

!     .. Executable Statements ..
Write (nout,*) 'E01BE_A1W_F Example Program Results'

!     Skip heading in data file

m = 1
Allocate (d(n),f(n),x(n),dx(n),df(n),px(m),pf(m),pd(m))

!     Create AD tape

!     Initialize x and r arrays using input data
Do r = 1, n
Read (nin,*) xr, fr
x(r) = xr
f(r) = fr
End Do

!     Create AD configuration data object
ifail = 0

!     Register variables to differentiate w.r.t.

!     Call the AD routine
ifail = 0

!     Evaluate interpolant and derivatives at a mid-point
px(1) = 0.5_nag_wp*(x(n/2)%value+x(n/2+1)%value)

Write (nout,*)
Write (nout,*) ' Derivatives calculated: First order adjoints'
Write (nout,*) ' Computational mode    : algorithmic'

!     Get derivative of interpolated value w.r.t data points and values

Write (nout,*)
Write (nout,99999) 'Interpolated value at x = ', px(1)%value, ' is: ',   &
pf(1)%value
99999 Format (1X,A,F7.3,A,E12.5)
Write (nout,*)
Write (nout,*) ' Derivatives of interpolated value w.r.t. x and f:'
Write (nout,*)
Write (nout,*) '    i      d/dx         d/df'
Do i = 1, n
Write (nout,99998) i, dx(i), df(i)
End Do
99998 Format (1X,I5,1X,E12.5,1X,E12.5)

!     Remove computational data object and tape
ifail = 0