```    Program f08pnfe

!     F08PNF Example Program Text

!     Mark 26 Release. NAG Copyright 2016.

!     .. Use Statements ..
Use nag_library, Only: f08pnz, nag_wp, x02ajf, x04dbf, zgees, zgemm,     &
zlange => f06uaf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nb = 64, nin = 5, nout = 6
!     .. Local Scalars ..
Complex (Kind=nag_wp)            :: alpha, beta
Real (Kind=nag_wp)               :: norm
Integer                          :: i, ifail, info, lda, ldc, ldd, ldvs, &
lwork, n, sdim
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: a(:,:), c(:,:), d(:,:), vs(:,:),   &
w(:), work(:)
Complex (Kind=nag_wp)            :: wdum(1)
Real (Kind=nag_wp), Allocatable  :: rwork(:)
Logical                          :: dummy(1)
Character (1)                    :: clabs(1), rlabs(1)
!     .. Intrinsic Procedures ..
Intrinsic                        :: cmplx, max, nint, real
!     .. Executable Statements ..
Write (nout,*) 'F08PNF Example Program Results'
Write (nout,*)
Flush (nout)
!     Skip heading in data file
lda = n
ldc = n
ldd = n
ldvs = n
Allocate (a(lda,n),vs(ldvs,n),c(ldc,n),d(ldd,n),w(n),rwork(n))

!     Use routine workspace query to get optimal workspace.
lwork = -1
!     The NAG name equivalent of zgees is f08pnf
Call zgees('Vectors (Schur)','No sort',f08pnz,n,a,lda,sdim,w,vs,ldvs,    &
wdum,lwork,rwork,dummy,info)

!     Make sure that there is enough workspace for block size nb.
lwork = max((nb+1)*n,nint(real(wdum(1))))
Allocate (work(lwork))

!     Read in the matrix A

!     Copy A into D
d(1:n,1:n) = a(1:n,1:n)

!     Print matrix A
!     ifail: behaviour on error exit
!            =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call x04dbf('General',' ',n,n,a,lda,'Bracketed','F7.4','Matrix A',       &
'Integer',rlabs,'Integer',clabs,80,0,ifail)

Write (nout,*)
Flush (nout)

!     Find the Schur factorization of A
!     The NAG name equivalent of zgees is f08pnf
Call zgees('Vectors (Schur)','No sort',f08pnz,n,a,lda,sdim,w,vs,ldvs,    &
work,lwork,rwork,dummy,info)

If (info>0) Then
Write (nout,99999) 'Failure in ZGEES. INFO =', info
Else

!       Compute A - Z*T*Z^H from the factorization of A and store in matrix D
!       The NAG name equivalent of zgemm is f06zaf
alpha = cmplx(1,kind=nag_wp)
beta = cmplx(0,kind=nag_wp)
Call zgemm('N','N',n,n,n,alpha,vs,ldvs,a,lda,beta,c,ldc)
alpha = cmplx(-1,kind=nag_wp)
beta = cmplx(1,kind=nag_wp)
Call zgemm('N','C',n,n,n,alpha,c,ldc,vs,ldvs,beta,d,ldd)

!       Find norm of matrix D and print warning if it is too large
!       f06uaf is the NAG name equivalent of the LAPACK auxiliary zlange
norm = zlange('O',ldd,n,d,ldd,rwork)
If (norm>x02ajf()**0.5_nag_wp) Then
Write (nout,*) 'Norm of A-(Z*T*Z^H) is much greater than 0.'
Write (nout,*) 'Schur factorization has failed.'
Else
!         Print eigenvalues.
Write (nout,*) 'Eigenvalues'
Write (nout,99998)(i,w(i),i=1,n)
End If
End If

99999 Format (1X,A,I4)
99998 Format (1X,I4,2X,' (',F7.4,',',F7.4,')',:)
End Program f08pnfe
```