Program f07ca_p0w_fe

!     F07CA_P0W_F Example Program Text
!     Mark 27 Release. NAG Copyright 2019.

!     .. Use Statements ..
      Use iso_c_binding, Only: c_ptr
      Use nagad_library, Only: f07ca_p0w_f
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6, nrhs = 1
!     .. Local Scalars ..
      Type (c_ptr)                     :: ad_handle
      Integer                          :: ifail, n
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: d(:), dl(:), du(:), x(:)
!     .. Executable Statements ..
      Write (nout,*) 'F07CA_P0W_F Example Program Results'
      Write (nout,*)
!     Skip heading in data file
      Read (nin,*)
      Read (nin,*) n

      Allocate (x(n),d(n),dl(n-1),du(n-1))

!     Read the tridiagonal matrix A and the right hand side B from
!     data file and initialize AD arrays

      Read (nin,*) du(1:n-1)
      Read (nin,*) d(1:n)
      Read (nin,*) dl(1:n-1)
      Read (nin,*) x(1:n)

!     Solve the equations Ax = b for x

!     The NAG name equivalent of dgtsv is f07ca_p0w_f
      ifail = 0
      Call f07ca_p0w_f(ad_handle,n,nrhs,dl,d,du,x,n,ifail)

      If (ifail==0) Then

!       Print primal solution

        Write (nout,*) 'Solution'
        Write (nout,99999) x(1:n)

      Else
        Write (nout,99998) 'Element U(', ifail, ',', ifail, ') is zero'
        Go To 100
      End If

99999 Format ((1X,7F11.4))
99998 Format (1X,A,I0,A,I0,A)

100   Continue

    End Program f07ca_p0w_fe