rft2.f90

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subroutine rft2(data, nr, kr)
!
!     ******************************************************************
!     * real fourier transform.                                        *
!     * input:  nr real coefficients                                   *
!     *             data(1),data(1+kr),....,data(1+(nr-1)*kr).         *
!     * output: nr/2+1 complex coefficients                            *
!     *            (data(1),      data(1+kr))                          *
!     *            (data(1+2*kr), data(1+3*kr))                        *
!     *             .............................                      *
!     *            (data(1+nr*kr),data(1+(nr+1)*kr).                   *
!     * the calling program should have data dimensioned with at least *
!     * (nr+1)*kr+1 elements. (i.e., nr+2 if increment kr=1).          *
!     * lasl routine may 75, calling fft2 and rtran2.                  *
!     ******************************************************************


  use itm_types

  implicit none

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

  call fft2(data(1), data(kr + 1), nr / 2, -(kr + kr))
  call rtran2(data, nr, kr, 1)

  return
end subroutine rft2