NAG Library Manual, Mark 28.5
Program f07gufe

!     F07GUF Example Program Text

!     Mark 28.5 Release. NAG Copyright 2022.

!     .. Use Statements ..
Use nag_library, Only: nag_wp, x02ajf, zlanhp => f06udf, zppcon, zpptrf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: anorm, rcond
Integer                          :: i, info, j, n
Character (1)                    :: uplo
!     .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: ap(:), work(:)
Real (Kind=nag_wp), Allocatable  :: rwork(:)
!     .. Executable Statements ..
Write (nout,*) 'F07GUF Example Program Results'
!     Skip heading in data file

Allocate (ap(n*(n+1)/2),work(2*n),rwork(n))

!     Read A from data file

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

!     Compute norm of A
!     f06udf is the NAG name equivalent of the LAPACK auxiliary zlanhp
anorm = zlanhp('1-norm',uplo,n,ap,rwork)

!     Factorize A
!     The NAG name equivalent of zpptrf is f07grf
Call zpptrf(uplo,n,ap,info)

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

!       Estimate condition number

!       The NAG name equivalent of zppcon is f07guf
Call zppcon(uplo,n,ap,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 f07gufe