subroutine radb5(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, ic, idp2, 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)
do concurrent(k=1:l1)
ti5 = cc(1, 3, k) + cc(1, 3, k)
ti4 = cc(1, 5, k) + cc(1, 5, k)
tr2 = cc(ido, 2, k) + cc(ido, 2, k)
tr3 = cc(ido, 4, k) + cc(ido, 4, k)
ch(1, k, 1) = cc(1, 1, k) + tr2 + tr3
cr2 = cc(1, 1, k) + tr11*tr2 + tr12*tr3
cr3 = cc(1, 1, k) + tr12*tr2 + tr11*tr3
ci5 = ti11*ti5 + ti12*ti4
ci4 = ti12*ti5 - ti11*ti4
ch(1, k, 2) = cr2 - ci5
ch(1, k, 3) = cr3 - ci4
ch(1, k, 4) = cr3 + ci4
ch(1, k, 5) = cr2 + ci5
end do
if (ido == 1) return
idp2 = ido + 2
do concurrent(k=1:l1, i=3:ido:2)
ic = idp2 - i
ti5 = cc(i, 3, k) + cc(ic, 2, k)
ti2 = cc(i, 3, k) - cc(ic, 2, k)
ti4 = cc(i, 5, k) + cc(ic, 4, k)
ti3 = cc(i, 5, k) - cc(ic, 4, k)
tr5 = cc(i - 1, 3, k) - cc(ic - 1, 2, k)
tr2 = cc(i - 1, 3, k) + cc(ic - 1, 2, k)
tr4 = cc(i - 1, 5, k) - cc(ic - 1, 4, k)
tr3 = cc(i - 1, 5, k) + cc(ic - 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 - 2)*dr2 - wa1(i - 1)*di2
ch(i, k, 2) = wa1(i - 2)*di2 + wa1(i - 1)*dr2
ch(i - 1, k, 3) = wa2(i - 2)*dr3 - wa2(i - 1)*di3
ch(i, k, 3) = wa2(i - 2)*di3 + wa2(i - 1)*dr3
ch(i - 1, k, 4) = wa3(i - 2)*dr4 - wa3(i - 1)*di4
ch(i, k, 4) = wa3(i - 2)*di4 + wa3(i - 1)*dr4
ch(i - 1, k, 5) = wa4(i - 2)*dr5 - wa4(i - 1)*di5
ch(i, k, 5) = wa4(i - 2)*di5 + wa4(i - 1)*dr5
end do
end subroutine radb5
