!   M01DZF Example Program Text
!   Mark 27.3 Release. NAG Copyright 2021.

    Module m01dzfe_mod

!     M01DZF Example Program Module:
!            Parameters and User-defined Routines

!     .. Use Statements ..
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Accessibility Statements ..
      Private
      Public                           :: compar
!     .. Parameters ..
      Integer, Parameter, Public       :: nin = 5, nout = 6
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable, Public, Save :: rv(:)
      Integer, Allocatable, Public, Save :: iv(:)
    Contains
      Function compar(i,j)

!       .. Function Return Value ..
        Logical                        :: compar
!       .. Scalar Arguments ..
        Integer, Intent (In)           :: i, j
!       .. Executable Statements ..
        If (iv(i)/=iv(j)) Then
          compar = iv(i) > iv(j)
        Else

          If (iv(i)<0) Then
            compar = rv(i) < rv(j)
          Else If (iv(i)>0) Then
            compar = rv(i) > rv(j)
          Else
            compar = i < j
          End If

        End If

        Return

      End Function compar
    End Module m01dzfe_mod
    Program m01dzfe

!     M01DZF Example Main Program

!     .. Use Statements ..
      Use m01dzfe_mod, Only: compar, iv, nin, nout, rv
      Use nag_library, Only: m01dzf, m01zaf
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Integer                          :: i, ifail, m1, m2
!     .. Local Arrays ..
      Integer, Allocatable             :: irank(:)
!     .. Executable Statements ..
      Write (nout,*) 'M01DZF Example Program Results'

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

      Read (nin,*) m2
      Allocate (iv(m2),rv(m2),irank(m2))

      m1 = 1

      Read (nin,*)(iv(i),rv(i),i=m1,m2)

      ifail = 0
      Call m01dzf(compar,m1,m2,irank,ifail)

      ifail = 0
      Call m01zaf(irank,m1,m2,ifail)

      Write (nout,*)
      Write (nout,*) '   Data in sorted order'
      Write (nout,*)

      Write (nout,99999)(iv(irank(i)),rv(irank(i)),i=m1,m2)

      Deallocate (iv,rv)

99999 Format (1X,I7,F7.1)
    End Program m01dzfe