Program f07wwfe

!     F07WWF Example Program Text

!     Mark 28.4 Release. NAG Copyright 2022.

!     .. Use Statements ..
      Use nag_library, Only: nag_wp, x04dbf, zpftrf, zpftri, ztfttr
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Integer                          :: i, ifail, info, k, lar1, lda, lenar, &
                                          n, q
      Character (1)                    :: transr, uplo
!     .. Local Arrays ..
      Complex (Kind=nag_wp), Allocatable :: a(:,:), ar(:)
      Character (1)                    :: clabs(1), rlabs(1)
!     .. Executable Statements ..
      Write (nout,*) 'F07WWF Example Program Results'
!     Skip heading in data file
      Read (nin,*)
      Read (nin,*) n, uplo, transr

      lenar = n*(n+1)/2
      lda = n
      Allocate (ar(lenar),a(lda,n))

!     Setup notional dimensions of RFP matrix AR
      k = n/2
      q = n - k
      If (transr=='N' .Or. transr=='n') Then
        lar1 = 2*k + 1
      Else
        lar1 = q
      End If

!     Read an RFP matrix into array AR
      Do i = 1, lar1
        Read (nin,*) ar(i:lenar:lar1)
      End Do

!     Factorize A
!     The NAG name equivalent of zpftrf is f07wrf
      Call zpftrf(transr,uplo,n,ar,info)

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

!       Compute inverse of A
!       The NAG name equivalent of zpftri is f07wwf
        Call zpftri(transr,uplo,n,ar,info)

!       Convert and print inverse
!       The NAG name equivalent of ztfttr is f01vhf
        Call ztfttr(transr,uplo,n,ar,a,lda,info)
        ifail = 0
        Call x04dbf(uplo,'Nonunit',n,n,a,lda,'Bracketed','F7.4','Inverse',     &
          'Integer',rlabs,'Integer',clabs,80,0,ifail)

      Else
        Write (nout,*) 'A is not positive definite'
      End If

    End Program f07wwfe