!
!  finestra_mobile.f
!
!  Free-Format Fortran Source File 
!  Generated by PGI Visual Fortran(R)
!  3/3/2015 9:37:37 AM
!
!______________________________________________________  
	  subroutine finestra_mobile(Ndati,t,eta,period) 
      implicit none
	  integer i,j,k,Nint,Nmax,Nyquist,Ndati,iscratch,Nup,Ndown
      integer itipo,Nwin,Niter,iter
      parameter(Nmax=10001)

	  real Ak(Nmax/2),Bk(Nmax/2),Amp(Nmax/2),Fase(Nmax/2)
      real t(Nmax),eta(Nmax),four(Nmax),scratch,alt(Nmax),scov
      real period,A0,omega,deltat,pigr,periodo_fisico
      real twin(Nmax),etawin(Nmax)

	  write(*,*)'DAMMI LA LUNGHEZZA DELLA FINESTRA'
      read(*,*) Nwin

	  Niter=Ndati-Nwin+1

! stampa su file
	  open(111,file='Fourier_mobile.out',
     >     status='unknown',access='sequential')

	  do iter=1,Niter
  
        do j=1,Nwin
          twin(j)=t(j+iter-1) 
          etawin(j)=eta(j+iter-1) 
	    end do

! CALCOLO VARIABILI DI LAVORO
	    period=twin(Nwin)-twin(1)
        omega=2*acos(-1.)/period
	    write(*,*)'Periodo della FINESTRA= ',period

! CALCOLO A0
        A0=0.
        do i=1,Nwin-1
          A0=A0+(etawin(i+1)+etawin(i))
        end do
        A0=A0/(Nwin-1)

!CALCOLO Ak
        Nyquist=(Nwin-1)/2
        do k=1,Nyquist
          Ak(k)=0.e0
          Bk(k)=0.e0
          do i=1,Nwin-1
            Ak(k)=Ak(k)+(etawin(i+1)*cos(k*omega*t(i+1))+
     >                 etawin(i)*cos(k*omega*t(i)))
            Bk(k)=Bk(k)+(etawin(i+1)*sin(k*omega*t(i+1))+
     >                 etawin(i)*sin(k*omega*t(i)))
          end do
          Ak(k)=Ak(k)/(Nwin-1)
          Bk(k)=Bk(k)/(Nwin-1)
		  Amp(k)=sqrt(Ak(k)**2+Bk(k)**2)
		  Fase(k)=atan2(Bk(k),Ak(k))
        end do

        write(111,'I4,1x,5(F15.5,1x)')0,omega*0,A0/2.,0.,A0/2.,0.
	    do k=1,Nyquist
          write(111,'I4,1x,5(F15.5,1x)')k,omega*k,Ak(k),Bk(k),
     >                                Amp(k),Fase(k)
	     end do
        write(111,*)
		
	  end do
	  close(111)

      return
	  end