rfi2.f90

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subroutine rfi2(data, nr, kr)                                       
!-----------------------------------------------------------------------
!  inverse of rft2.                                               
!  when using rfi2 it is necessary to have vanishing imaginary   
!  parts of the first and last element of the input vector: 
!  data(1+kr)=data(1+(nr+1)*kr)=0.                              
!  the calling program should have data dimensioned with at least 
!    (nr+1)*kr+1 elements.                                          
!  lasl routine may 75, calling rtran2 and fft2.                  
! -----------------------------------------------------------------------

  use itm_types

  implicit none

  integer(itm_i4), intent(in) :: nr, kr
  real(r8), dimension((nr + 1) * kr + 1), intent(inout) :: data

  real(r8) :: fni
  integer(itm_i4) :: mr, i

  call rtran2(data, nr, kr, -1)

  mr = nr * kr
  fni = 2._r8 / dble(nr)

  do i = 1, mr, kr
    data(i) = fni * data(i)
  end do

  call fft2(data(1), data(kr + 1), nr/2, (kr + kr))

  return
end subroutine rfi2