```    Program e01tkfe

!     E01TKF Example Program Text

!     Mark 26.1 Release. NAG Copyright 2017.

!     .. Use Statements ..
Use nag_library, Only: e01tkf, e01tlf, nag_wp
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Integer                          :: i, ifail, liq, lrq, m, n, nq, nw
!     .. Local Arrays ..
Real (Kind=nag_wp), Allocatable  :: f(:), q(:), qx(:,:), rq(:), x(:,:),  &
xe(:,:)
Integer, Allocatable             :: iq(:)
!     .. Executable Statements ..
Write (nout,*) 'E01TKF Example Program Results'

!     Skip heading in data file

!     Input the number of nodes.
liq = 2*m + 1
lrq = 15*m + 9
Allocate (x(4,m),f(m),iq(liq),rq(lrq))

!     Input the data points X and F.
Do i = 1, m
Read (nin,*) x(1:4,i), f(i)
End Do

!     Generate the interpolant.
nq = 0
nw = 0

ifail = 0
Call e01tkf(m,x,f,nw,nq,iq,rq,ifail)

!     Input the number of evaluation points.
Allocate (xe(4,n),q(n),qx(4,n))

!     Input the evaluation points.
Do i = 1, n
End Do

!     Evaluate the interpolant using E01TLF.
ifail = 1
Call e01tlf(m,x,f,iq,rq,n,xe,q,qx,ifail)
If (ifail==0 .Or. ifail==3) Then
If (ifail==3) Then
Write (nout,*) 'Some values below have been extrapolated'
Write (nout,*)
End If
Write (nout,99998) 'Interpolated Evaluation Points', 'Values'
Write (nout,99997)
Write (nout,99996)(i,i=1,4)
Write (nout,99997)
Do i = 1, n
Write (nout,99999) i, xe(1:4,i), q(i)
End Do
Else
Write (nout,99995) 'Evaluation routine returned with IFAIL = ', ifail
End If

99999 Format (1X,I4,1X,4F10.4,1X,F10.4)
99998 Format (/,4X,'   |',5X,A31,5X,'|',A7)
99997 Format (4X,'---|',41('-'),'+',8('-'))
99996 Format (4X,'I  |',4(2X,'XE(I,',I1,')',1X),1X,'|',2X,'Q(I)')
99995 Format (1X,A,I4)
End Program e01tkfe
```