subroutine rfftf1(n,c,Ch,Wa,Ifac)
use fftpack_kind
implicit none
real(rk) :: c , Ch , Wa
integer :: i , idl1 , ido , Ifac , ip , iw , ix2 , ix3 , ix4 , k1 , &
kh , l1 , l2 , n , na , nf
dimension Ch(*) , c(*) , Wa(*) , Ifac(*)
nf = Ifac(2)
na = 1
l2 = n
iw = n
do k1 = 1 , nf
kh = nf - k1
ip = Ifac(kh+3)
l1 = l2/ip
ido = n/l2
idl1 = ido*l1
iw = iw - (ip-1)*ido
na = 1 - na
if ( ip==4 ) then
ix2 = iw + ido
ix3 = ix2 + ido
if ( na/=0 ) then
call radf4(ido,l1,Ch,c,Wa(iw),Wa(ix2),Wa(ix3))
else
call radf4(ido,l1,c,Ch,Wa(iw),Wa(ix2),Wa(ix3))
endif
elseif ( ip/=2 ) then
if ( ip==3 ) then
ix2 = iw + ido
if ( na/=0 ) then
call radf3(ido,l1,Ch,c,Wa(iw),Wa(ix2))
else
call radf3(ido,l1,c,Ch,Wa(iw),Wa(ix2))
endif
elseif ( ip/=5 ) then
if ( ido==1 ) na = 1 - na
if ( na/=0 ) then
call radfg(ido,ip,l1,idl1,Ch,Ch,Ch,c,c,Wa(iw))
na = 0
else
call radfg(ido,ip,l1,idl1,c,c,c,Ch,Ch,Wa(iw))
na = 1
endif
else
ix2 = iw + ido
ix3 = ix2 + ido
ix4 = ix3 + ido
if ( na/=0 ) then
call radf5(ido,l1,Ch,c,Wa(iw),Wa(ix2),Wa(ix3),Wa(ix4))
else
call radf5(ido,l1,c,Ch,Wa(iw),Wa(ix2),Wa(ix3),Wa(ix4))
endif
endif
elseif ( na/=0 ) then
call radf2(ido,l1,Ch,c,Wa(iw))
else
call radf2(ido,l1,c,Ch,Wa(iw))
endif
l2 = l1
enddo
if ( na==1 ) return
do i = 1 , n
c(i) = Ch(i)
enddo
end subroutine rfftf1
