```    Program f01vdfe

!     F01VDF Example Program Text

!     Mark 27.0 Release. NAG Copyright 2019.

!     .. Use Statements ..
Use nag_library, Only: nag_wp, x04dbf, ztpttr
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: inc1 = 1, indent = 0, ncols = 80,    &
nin = 5, nout = 6
Character (1), Parameter         :: brac = 'B', diag = 'N',              &
intlabel = 'I', matrix = 'G',        &
nolabel = 'N'
Character (4), Parameter         :: form = 'F5.2'
!     .. Local Scalars ..
Integer                          :: i, ifail, info, lda, lenap, n
Character (18)                   :: title
Character (1)                    :: uplo
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: a(:,:), ap(:)
Character (1)                    :: clabs(1), rlabs(1)
!     .. Executable Statements ..
Write (nout,*) 'F01VDF Example Program Results'
!     Skip heading in data file
Write (nout,*)
Flush (nout)
lda = n
lenap = (n*(n+1))/2
Allocate (a(lda,n),ap(lenap))

!     Read a packed vector of order n
Do i = 1, lenap
End Do

!     Print the packed vector
title = 'Packed Matrix AP: '
ifail = 0
Call x04dbf(matrix,diag,lenap,inc1,ap,lenap,brac,form,title,intlabel,    &
rlabs,nolabel,clabs,ncols,indent,ifail)

Write (nout,*)
Flush (nout)

!     Convert to triangular form
!     The NAG name equivalent of ztpttr is f01vdf
Call ztpttr(uplo,n,ap,a,lda,info)

!     Print the unpacked matrix
title = 'Unpacked Matrix A:'
ifail = 0
Call x04dbf(uplo,diag,n,n,a,lda,brac,form,title,intlabel,rlabs,intlabel, &
clabs,ncols,indent,ifail)

End Program f01vdfe
```