subroutine mradb2 ( m, ido, l1, cc, im1, in1, ch, im2, in2, wa1 )

!*****************************************************************************80
!
!! MRADB2 is an FFTPACK5 auxiliary routine.
!
!
!    Copyright (C) 1995-2004, Scientific Computing Division,
!    University Corporation for Atmospheric Research
!
!  Modified:
!
!    27 March 2009
!
!  Author:
!
!    Paul Swarztrauber
!    Richard Valent
!
!  Reference:
!
!    Paul Swarztrauber,
!    Vectorizing the Fast Fourier Transforms,
!    in Parallel Computations,
!    edited by G. Rodrigue,
!    Academic Press, 1982.
!
!    Paul Swarztrauber,
!    Fast Fourier Transform Algorithms for Vector Computers,
!    Parallel Computing, pages 45-63, 1984.
!
!  Parameters:
!
  implicit none

  integer ( kind = 4 ) ido
  integer ( kind = 4 ) in1
  integer ( kind = 4 ) in2
  integer ( kind = 4 ) l1

  real ( kind = 4 ) cc(in1,ido,2,l1)
  real ( kind = 4 ) ch(in2,ido,l1,2)
  integer ( kind = 4 ) i
  integer ( kind = 4 ) ic
  integer ( kind = 4 ) idp2
  integer ( kind = 4 ) im1
  integer ( kind = 4 ) im2
  integer ( kind = 4 ) k
  integer ( kind = 4 ) m
  integer ( kind = 4 ) m1
  integer ( kind = 4 ) m1d
  integer ( kind = 4 ) m2
  integer ( kind = 4 ) m2s
  real ( kind = 4 ) wa1(ido)

  m1d = ( m - 1 ) * im1 + 1
  m2s = 1 - im2

  do k = 1, l1
    m2 = m2s
    do m1 = 1, m1d, im1
      m2 = m2 + im2
      ch(m2,1,k,1) = cc(m1,1,1,k) + cc(m1,ido,2,k)
      ch(m2,1,k,2) = cc(m1,1,1,k) - cc(m1,ido,2,k)
    end do
  end do

  if ( ido < 2 ) then
    return
  end if

  if ( 2 < ido ) then

    idp2 = ido + 2

    do k = 1, l1
      do i = 3, ido, 2
        ic = idp2 - i
        m2 = m2s
        do m1 = 1, m1d, im1
          m2 = m2 + im2
          ch(m2,i-1,k,1) = cc(m1,i-1,1,k) + cc(m1,ic-1,2,k)
          ch(m2,i,k,1)   = cc(m1,i,1,k) - cc(m1,ic,2,k)
          ch(m2,i-1,k,2) = wa1(i-2) * ( cc(m1,i-1,1,k) - cc(m1,ic-1,2,k) ) &
                         - wa1(i-1) * ( cc(m1,i,1,k)   + cc(m1,ic,2,k) )
          ch(m2,i,k,2)   = wa1(i-2) * ( cc(m1,i,1,k)   + cc(m1,ic,2,k) ) &
                         + wa1(i-1) * ( cc(m1,i-1,1,k) - cc(m1,ic-1,2,k) )
        end do
      end do
    end do

    if ( mod ( ido, 2 ) == 1 ) then
      return
    end if

  end if

  do k = 1, l1
    m2 = m2s
    do m1 = 1, m1d, im1
      m2 = m2 + im2
      ch(m2,ido,k,1) = cc(m1,ido,1,k) + cc(m1,ido,1,k)
      ch(m2,ido,k,2) = -( cc(m1,1,2,k) + cc(m1,1,2,k) )
    end do
  end do

  return
end
