```    Program f08sefe

!     F08SEF Example Program Text

!     Mark 26.1 Release. NAG Copyright 2017.

!     .. Use Statements ..
Use nag_library, Only: dpotrf, dsterf, dsygst, dsytrd, nag_wp
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Integer                          :: i, info, lda, ldb, lwork, n
Character (1)                    :: uplo
!     .. Local Arrays ..
Real (Kind=nag_wp), Allocatable  :: a(:,:), b(:,:), d(:), e(:), tau(:),  &
work(:)
!     .. Executable Statements ..
Write (nout,*) 'F08SEF Example Program Results'
!     Skip heading in data file
lda = n
ldb = n
lwork = 64*n
Allocate (a(lda,n),b(ldb,n),d(n),e(n-1),tau(n),work(lwork))

!     Read A and B from data file

If (uplo=='U') Then
Else If (uplo=='L') Then
End If

!     Compute the Cholesky factorization of B
!     The NAG name equivalent of dpotrf is f07fdf
Call dpotrf(uplo,n,b,ldb,info)

Write (nout,*)
If (info>0) Then
Write (nout,*) 'B is not positive definite.'
Else

!       Reduce the problem to standard form C*y = lambda*y, storing
!       the result in A
!       The NAG name equivalent of dsygst is f08sef
Call dsygst(1,uplo,n,a,lda,b,ldb,info)

!       Reduce C to tridiagonal form T = (Q**T)*C*Q
!       The NAG name equivalent of dsytrd is f08fef
Call dsytrd(uplo,n,a,lda,d,e,tau,work,lwork,info)

!       Calculate the eigenvalues of T (same as C)
!       The NAG name equivalent of dsterf is f08jff
Call dsterf(n,d,e,info)

If (info>0) Then
Write (nout,*) 'Failure to converge.'
Else

!         Print eigenvalues

Write (nout,*) 'Eigenvalues'
Write (nout,99999) d(1:n)
End If
End If

99999 Format (3X,(9F8.4))
End Program f08sefe
```