!   D05AAF Example Program Text
!   Mark 27.3 Release. NAG Copyright 2021.

    Module d05aafe_mod

!     D05AAF 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                           :: g, k1, k2
!     .. Parameters ..
      Real (Kind=nag_wp), Parameter, Public :: a = 0.0_nag_wp
      Real (Kind=nag_wp), Parameter, Public :: b = 1.0_nag_wp
      Real (Kind=nag_wp), Parameter, Public :: lambda = 1.0_nag_wp
      Real (Kind=nag_wp), Parameter, Public :: xval = 0.1_nag_wp
      Integer, Parameter, Public       :: ind = 2, n = 5, nout = 6
      Integer, Parameter, Public       :: ldw1 = n
      Integer, Parameter, Public       :: ldw2 = 2*n + 2
    Contains
      Function k1(x,s)

!       .. Function Return Value ..
        Real (Kind=nag_wp)             :: k1
!       .. Scalar Arguments ..
        Real (Kind=nag_wp), Intent (In) :: s, x
!       .. Executable Statements ..
        k1 = s*(1.0_nag_wp-x)

        Return
      End Function k1
      Function k2(x,s)

!       .. Function Return Value ..
        Real (Kind=nag_wp)             :: k2
!       .. Scalar Arguments ..
        Real (Kind=nag_wp), Intent (In) :: s, x
!       .. Executable Statements ..
        k2 = x*(1.0_nag_wp-s)

        Return
      End Function k2
      Function g(x)

!       .. Use Statements ..
        Use nag_library, Only: x01aaf
!       .. Function Return Value ..
        Real (Kind=nag_wp)             :: g
!       .. Scalar Arguments ..
        Real (Kind=nag_wp), Intent (In) :: x
!       .. Local Scalars ..
        Real (Kind=nag_wp)             :: pi
!       .. Intrinsic Procedures ..
        Intrinsic                      :: sin
!       .. Executable Statements ..
        pi = x01aaf(pi)
        g = sin(pi*x)*(1.0_nag_wp-1.0_nag_wp/(pi*pi))

        Return
      End Function g
    End Module d05aafe_mod
    Program d05aafe

!     D05AAF Example Main Program

!     .. Use Statements ..
      Use d05aafe_mod, Only: a, b, g, ind, k1, k2, lambda, ldw1, ldw2, n,      &
                             nout, xval
      Use nag_library, Only: c06dcf, d05aaf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Integer                          :: ifail, is
!     .. Local Arrays ..
      Real (Kind=nag_wp)               :: ans(1), x(1)
      Real (Kind=nag_wp), Allocatable  :: c(:), f(:), w1(:,:), w2(:,:), wd(:)
!     .. Executable Statements ..
      Write (nout,*) 'D05AAF Example Program Results'

      Allocate (c(n),f(n),w1(ldw1,ldw2),w2(ldw2,4),wd(ldw2))

      ifail = 0
      Call d05aaf(lambda,a,b,k1,k2,g,f,c,n,ind,w1,w2,wd,ldw1,ldw2,ifail)

      Write (nout,99999)
      Write (nout,99998) c(1:n)

      x(1) = xval

      Select Case (ind)
      Case (1)
        is = 3
      Case (2)
        is = 2
      Case Default
        is = 1
      End Select

      ifail = 0
      Call c06dcf(x,1,a,b,c,n,is,ans,ifail)

      Write (nout,99997) 'X=', x, '    ANS=', ans

99999 Format (/,1X,'Kernel is centro-symmetric and G is even so the ',         &
        'solution is even',/,/,1X,'Chebyshev coefficients',/)
99998 Format (1X,5E14.4,/)
99997 Format (1X,A,F5.2,A,1F10.4)
    End Program d05aafe