passb5 Subroutine

      subroutine passb5(ido, l1, cc, ch, wa1, wa2, wa3, wa4)
         use fftpack_kind, only: dp => rk
         implicit none
         integer, intent(in) :: ido, l1
         real(dp), intent(in) :: cc(ido, 5, l1), wa1(*), wa2(*), wa3(*), wa4(*)
         real(dp), intent(out) :: ch(ido, l1, 5)
         real(dp) :: ci2, ci3, ci4, ci5, cr2, cr3, &
                     cr4, cr5, di2, di3, di4, di5, dr2, dr3, &
                     dr4, dr5
         real(dp) :: ti2, ti3, ti4, ti5, tr2, tr3, &
                     tr4, tr5
         integer :: i, k
         real(dp), parameter :: pi = acos(-1.0_dp)
         real(dp), parameter :: tr11 = cos(2.0_dp*pi/5.0_dp)
         real(dp), parameter :: ti11 = sin(2.0_dp*pi/5.0_dp)
         real(dp), parameter :: tr12 = cos(4.0_dp*pi/5.0_dp)
         real(dp), parameter :: ti12 = sin(4.0_dp*pi/5.0_dp)
         if (ido /= 2) then
            do k = 1, l1
               do i = 2, ido, 2
                  ti5 = cc(i, 2, k) - cc(i, 5, k)
                  ti2 = cc(i, 2, k) + cc(i, 5, k)
                  ti4 = cc(i, 3, k) - cc(i, 4, k)
                  ti3 = cc(i, 3, k) + cc(i, 4, k)
                  tr5 = cc(i - 1, 2, k) - cc(i - 1, 5, k)
                  tr2 = cc(i - 1, 2, k) + cc(i - 1, 5, k)
                  tr4 = cc(i - 1, 3, k) - cc(i - 1, 4, k)
                  tr3 = cc(i - 1, 3, k) + cc(i - 1, 4, k)
                  ch(i - 1, k, 1) = cc(i - 1, 1, k) + tr2 + tr3
                  ch(i, k, 1) = cc(i, 1, k) + ti2 + ti3
                  cr2 = cc(i - 1, 1, k) + tr11*tr2 + tr12*tr3
                  ci2 = cc(i, 1, k) + tr11*ti2 + tr12*ti3
                  cr3 = cc(i - 1, 1, k) + tr12*tr2 + tr11*tr3
                  ci3 = cc(i, 1, k) + tr12*ti2 + tr11*ti3
                  cr5 = ti11*tr5 + ti12*tr4
                  ci5 = ti11*ti5 + ti12*ti4
                  cr4 = ti12*tr5 - ti11*tr4
                  ci4 = ti12*ti5 - ti11*ti4
                  dr3 = cr3 - ci4
                  dr4 = cr3 + ci4
                  di3 = ci3 + cr4
                  di4 = ci3 - cr4
                  dr5 = cr2 + ci5
                  dr2 = cr2 - ci5
                  di5 = ci2 - cr5
                  di2 = ci2 + cr5
                  ch(i - 1, k, 2) = wa1(i - 1)*dr2 - wa1(i)*di2
                  ch(i, k, 2) = wa1(i - 1)*di2 + wa1(i)*dr2
                  ch(i - 1, k, 3) = wa2(i - 1)*dr3 - wa2(i)*di3
                  ch(i, k, 3) = wa2(i - 1)*di3 + wa2(i)*dr3
                  ch(i - 1, k, 4) = wa3(i - 1)*dr4 - wa3(i)*di4
                  ch(i, k, 4) = wa3(i - 1)*di4 + wa3(i)*dr4
                  ch(i - 1, k, 5) = wa4(i - 1)*dr5 - wa4(i)*di5
                  ch(i, k, 5) = wa4(i - 1)*di5 + wa4(i)*dr5
               end do
            end do
         else
            do k = 1, l1
               ti5 = cc(2, 2, k) - cc(2, 5, k)
               ti2 = cc(2, 2, k) + cc(2, 5, k)
               ti4 = cc(2, 3, k) - cc(2, 4, k)
               ti3 = cc(2, 3, k) + cc(2, 4, k)
               tr5 = cc(1, 2, k) - cc(1, 5, k)
               tr2 = cc(1, 2, k) + cc(1, 5, k)
               tr4 = cc(1, 3, k) - cc(1, 4, k)
               tr3 = cc(1, 3, k) + cc(1, 4, k)
               ch(1, k, 1) = cc(1, 1, k) + tr2 + tr3
               ch(2, k, 1) = cc(2, 1, k) + ti2 + ti3
               cr2 = cc(1, 1, k) + tr11*tr2 + tr12*tr3
               ci2 = cc(2, 1, k) + tr11*ti2 + tr12*ti3
               cr3 = cc(1, 1, k) + tr12*tr2 + tr11*tr3
               ci3 = cc(2, 1, k) + tr12*ti2 + tr11*ti3
               cr5 = ti11*tr5 + ti12*tr4
               ci5 = ti11*ti5 + ti12*ti4
               cr4 = ti12*tr5 - ti11*tr4
               ci4 = ti12*ti5 - ti11*ti4
               ch(1, k, 2) = cr2 - ci5
               ch(1, k, 5) = cr2 + ci5
               ch(2, k, 2) = ci2 + cr5
               ch(2, k, 3) = ci3 + cr4
               ch(1, k, 3) = cr3 - ci4
               ch(1, k, 4) = cr3 + ci4
               ch(2, k, 4) = ci3 - cr4
               ch(2, k, 5) = ci2 - cr5
            end do
         end if
      end subroutine passb5