Program c06fcfe

!     C06FCF Example Program Text

!     Mark 30.2 Release. NAG Copyright 2024.

!     .. Use Statements ..
      Use nag_library, Only: c06fcf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Integer                          :: ieof, ifail, j, n
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: work(:), x(:), xx(:), y(:), yy(:)
!     .. Executable Statements ..
      Write (nout,*) 'C06FCF Example Program Results'
!     Skip heading in data file
      Read (nin,*)
loop: Do
        Read (nin,*,Iostat=ieof) n
        If (ieof<0) Then
          Exit loop
        End If

        Allocate (x(0:n-1),xx(0:n-1),y(0:n-1),yy(0:n-1),work(n))
        Read (nin,*)(x(j),y(j),j=0,n-1)
        xx(0:n-1) = x(0:n-1)
        yy(0:n-1) = y(0:n-1)

!       ifail: behaviour on error exit
!              =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
        ifail = 0
        Call c06fcf(x,y,n,work,ifail)

        Write (nout,*)
        Write (nout,*) 'Components of discrete Fourier transform'
        Write (nout,*)
        Write (nout,*) '          Real      Imag'
        Write (nout,*)
        Write (nout,99999)(j,x(j),y(j),j=0,n-1)

        y(0:n-1) = -y(0:n-1)
        Call c06fcf(x,y,n,work,ifail)
        y(0:n-1) = -y(0:n-1)

        Write (nout,*)
        Write (nout,*) 'Original sequence as restored by inverse transform'
        Write (nout,*)
        Write (nout,*) '             Original                 Restored'
        Write (nout,*) '          Real      Imag           Real      Imag'
        Write (nout,*)
        Write (nout,99998)(j,xx(j),yy(j),x(j),y(j),j=0,n-1)
        Deallocate (x,xx,y,yy,work)
      End Do loop

99999 Format (1X,I5,2F10.5)
99998 Format (1X,I5,2F10.5,5X,2F10.5)
    End Program c06fcfe