NAG Library Manual, Mark 28.3
```    Program f01zafe

!     F01ZAF Example Program Text

!     Mark 28.3 Release. NAG Copyright 2022.

!     .. Use Statements ..
Use nag_library, Only: f01zaf, nag_wp, x04cbf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Integer                          :: i, ifail, lb, lda, lenb, n
Character (1)                    :: diag, uplo
!     .. Local Arrays ..
Real (Kind=nag_wp), Allocatable  :: a(:,:), b(:)
Character (1)                    :: clabs(1), rlabs(1)
!     .. Executable Statements ..
Write (nout,*) 'F01ZAF Example Program Results'
!     Skip heading in data file
Write (nout,*)
Flush (nout)
lda = n
lenb = (n*(n+1))/2
Allocate (a(lda,n),b(lenb))
!     Read a triangular matrix of order n
Do i = 1, n
End Do

!     ifail: behaviour on error exit
!             =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
!     Print the unpacked matrix
Call x04cbf(uplo,diag,n,n,a,lda,'F5.2','Unpacked Matrix A:','I',rlabs,   &
'I',clabs,80,0,ifail)

Write (nout,*)
Flush (nout)

!     Convert to packed vector form
ifail = 0
Call f01zaf('Pack',uplo,diag,n,a,lda,b,ifail)

lb = n*(n+1)/2

!     Print the packed vector
ifail = 0
Call x04cbf('G','X',lb,1,b,lb,'F5.2','Packed Vector B:','I',rlabs,'N',   &
clabs,80,0,ifail)

End Program f01zafe
```