```    Program f07gtfe

!     F07GTF Example Program Text

!     Mark 27.1 Release. NAG Copyright 2020.

!     .. Use Statements ..
Use nag_library, Only: f06kcf, nag_wp, x02ajf, x02amf, x02bhf, x04ddf,   &
zdscal, zppequ
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Real (Kind=nag_wp), Parameter    :: one = 1.0_nag_wp
Real (Kind=nag_wp), Parameter    :: thresh = 0.1_nag_wp
Integer, Parameter               :: nin = 5, nout = 6
Character (1), Parameter         :: uplo = 'U'
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: amax, big, scond, small
Integer                          :: i, ifail, info, j, jinc, jj, n
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: ap(:)
Real (Kind=nag_wp), Allocatable  :: s(:)
Character (1)                    :: clabs(1), rlabs(1)
!     .. Intrinsic Procedures ..
Intrinsic                        :: real
!     .. Executable Statements ..
Write (nout,*) 'F07GTF Example Program Results'
Write (nout,*)
Flush (nout)
!     Skip heading in data file

Allocate (ap((n*(n+1))/2),s(n))

!     Read the upper or lower triangular part of the matrix A from
!     data file

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

!     Print the matrix A

!     ifail: behaviour on error exit
!             =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call x04ddf(uplo,'Non-unit diagonal',n,ap,'Bracketed','1P,E10.2',        &
'Matrix A','Integer',rlabs,'Integer',clabs,80,0,ifail)

Write (nout,*)

!     Compute diagonal scaling factors
!     The NAG name equivalent of zppequ is f07gtf
Call zppequ(uplo,n,ap,s,scond,amax,info)

If (info>0) Then
Write (nout,99999) 'Diagonal element', info, ' of A is non positive'
Else

!       Print SCOND, AMAX and the scale factors

Write (nout,99998) 'SCOND =', scond, ', AMAX =', amax
Write (nout,*)
Write (nout,*) 'Diagonal scaling factors'
Write (nout,99997) s(1:n)
Write (nout,*)
Flush (nout)

!       Compute values close to underflow and overflow

small = x02amf()/(x02ajf()*real(x02bhf(),kind=nag_wp))
big = one/small
If ((scond<thresh) .Or. (amax<small) .Or. (amax>big)) Then

!         Scale A

If (uplo=='U') Then

!           The NAG name equivalent of zdscal is f06jdf
jj = 1
Do j = 1, n
Call zdscal(j,s(j),ap(jj),1)
Call f06kcf(j,s,1,ap(jj),1)
jj = jj + j
End Do
Else If (uplo=='L') Then
jj = 1
jinc = n
Do j = 1, n
Call zdscal(jinc,s(j),ap(jj),1)
Call f06kcf(jinc,s(j),1,ap(jj),1)
jj = jj + jinc
jinc = jinc - 1
End Do
End If

!         Print the scaled matrix

ifail = 0
Call x04ddf(uplo,'Non-unit diagonal',n,ap,'Bracketed','F8.4',        &
'Scaled matrix','Integer',rlabs,'Integer',clabs,80,0,ifail)

End If
End If

99999 Format (1X,A,I4,A)
99998 Format (1X,2(A,1P,E8.1))
99997 Format ((1X,1P,7E11.1))
End Program f07gtfe
```