Program s17alfe

!     S17ALF Example Program Text

!     Mark 27.3 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use nag_library, Only: nag_wp, s17alf, x02ajf
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: a, rel
      Integer                          :: i, ifail, mode, n
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: x(:)
!     .. Intrinsic Procedures ..
      Intrinsic                        :: sqrt
!     .. Executable Statements ..
      Write (nout,*) 'S17ALF Example Program Results'

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

      rel = sqrt(x02ajf())
      Read (nin,*) a, n, mode
      Allocate (x(n))

      ifail = 0
      Call s17alf(a,n,mode,rel,x,ifail)

      Write (nout,*)
      Write (nout,*) '   A   N   MODE        REL'
      Write (nout,*) '                 (machine-dependent)'
      Write (nout,*)
      Write (nout,99999) a, n, mode, rel
      Write (nout,*)

      Select Case (mode)
      Case (1)
        Write (nout,*) 'Leading N positive zeros of J'
      Case (2)
        Write (nout,*) 'Leading N positive zeros of Y'
      Case (3)

        If (a==0.0E0_nag_wp) Then
          Write (nout,*) 'Leading N non-negative zeros of J'''
        Else
          Write (nout,*) 'Leading N positive zeros of J'''
        End If

      Case (4)
        Write (nout,*) 'Leading N positive zeros of Y'''
      End Select

      Write (nout,*)
      Write (nout,*) 'X ='
      Write (nout,99998)(x(i),i=1,n)
      Write (nout,*)

99999 Format (1X,F4.1,I4,I7,4X,1P,E9.1)
99998 Format (1P,(E12.4))
    End Program s17alfe