Program e02acfe

!     E02ACF Example Program Text

!     Mark 26.2 Release. NAG Copyright 2017.

!     .. Use Statements ..
      Use nag_library, Only: e02acf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: m1 = 6, n = 21, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: ref, s, t, z
      Integer                          :: i, j
!     .. Local Arrays ..
      Real (Kind=nag_wp)               :: a(m1), x(n), y(n)
!     .. Intrinsic Procedures ..
      Intrinsic                        :: exp, real
!     .. Executable Statements ..
      Write (nout,*) 'E02ACF Example Program Results'

      x(1:n) = real((/(i-1,i=1,n)/),kind=nag_wp)/real(n-1,kind=nag_wp)
      y(1:n) = exp(x(1:n))

      Call e02acf(x,y,n,a,m1,ref)

      Write (nout,*)
      Write (nout,*) '   Polynomial coefficients'
      Write (nout,99998)(a(i),i=1,m1)
      Write (nout,*)
      Write (nout,99997) '   Reference deviation = ', ref
      Write (nout,*)
      Write (nout,*) '  X     exp(X)    Fit     Residual'

      Do j = 1, n, 2
        z = x(j)

        s = a(m1)

        Do i = m1 - 1, 1, -1
          s = s*z + a(i)
        End Do

        t = y(j)
        Write (nout,99999) z, s, t, s - t
      End Do

99999 Format (1X,F5.2,2F9.4,E11.2)
99998 Format (6X,E12.4)
99997 Format (1X,A,E10.2)
    End Program e02acfe