NAG Library Manual, Mark 27.2
```    Program f07hufe

!     F07HUF Example Program Text

!     Mark 27.2 Release. NAG Copyright 2021.

!     .. Use Statements ..
Use nag_library, Only: nag_wp, x02ajf, zlanhb => f06uef, zpbcon, zpbtrf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: anorm, rcond
Integer                          :: i, info, j, kd, ldab, n
Character (1)                    :: uplo
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: ab(:,:), work(:)
Real (Kind=nag_wp), Allocatable  :: rwork(:)
!     .. Intrinsic Procedures ..
Intrinsic                        :: max, min
!     .. Executable Statements ..
Write (nout,*) 'F07HUF Example Program Results'
!     Skip heading in data file
ldab = kd + 1
Allocate (ab(ldab,n),work(2*n),rwork(n))

!     Read A from data file

If (uplo=='U') Then
Do i = 1, n
End Do
Else If (uplo=='L') Then
Do i = 1, n
End Do
End If

!     Compute norm of A
!     f06uef is the NAG name equivalent of the LAPACK auxiliary zlanhb
anorm = zlanhb('1-norm',uplo,n,kd,ab,ldab,rwork)

!     Factorize A
!     The NAG name equivalent of zpbtrf is f07hrf
Call zpbtrf(uplo,n,kd,ab,ldab,info)

Write (nout,*)
If (info==0) Then

!       Estimate condition number
!       The NAG name equivalent of zpbcon is f07huf
Call zpbcon(uplo,n,kd,ab,ldab,anorm,rcond,work,rwork,info)

If (rcond>=x02ajf()) Then
Write (nout,99999) 'Estimate of condition number =',                 &
1.0_nag_wp/rcond
Else
Write (nout,*) 'A is singular to working precision'
End If
Else
Write (nout,*) 'A is not positive definite'
End If

99999 Format (1X,A,1P,E10.2)
End Program f07hufe
```