Program f01jafe

!     F01JAF Example Program Text

!     Mark 29.1 Release. NAG Copyright 2023.

!     .. Use Statements ..
      Use nag_library, Only: f01jaf, nag_wp, x02ajf, x04caf
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: conda, cond_rel, eps, norma, normfa
      Integer                          :: i, ifail, lda, n
      Character (4)                    :: fun
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: a(:,:)
!     .. Executable Statements ..
      Write (nout,*) 'F01JAF Example Program Results'
      Write (nout,*)
      Flush (nout)

!     Skip heading in data file
      Read (nin,*)
      Read (nin,*) n, fun

      lda = n
      Allocate (a(lda,n))

!     Read A from data file
      Read (nin,*)(a(i,1:n),i=1,n)

!     Display A
      ifail = 0
      Call x04caf('G','N',n,n,a,lda,'A',ifail)

!     Find absolute condition number estimate
      ifail = 0
      Call f01jaf(fun,n,a,lda,conda,norma,normfa,ifail)

      If (ifail==0) Then
!       Print solution
        Write (nout,*)
        Write (nout,*) 'F(A) = ', fun, '(A)'
        Write (nout,99999) 'Estimated absolute condition number is: ', conda

!       Find relative condition number estimate
        eps = x02ajf()
        If (normfa>eps) Then
          cond_rel = conda*norma/normfa
          Write (nout,99999) 'Estimated relative condition number is: ',       &
            cond_rel
        Else
          Write (nout,99998) 'The estimated norm of f(A) is effectively zero', &
            'and so the relative condition number is undefined.'
        End If
      End If

99999 Format (1X,A,F7.2)
99998 Format (/,1X,A,/,1X,A)

    End Program f01jafe