1subroutine tweak1(ca,jz,f0,cb)
2
3! Shift frequency of analytic signal ca, with output to cb
4
5  complex ca(jz),cb(jz)
6  real*8 twopi
7  complex*16 w,wstep
8  complex w4
9  data twopi/0.d0/
10  save twopi
11
12  if(twopi.eq.0.d0) twopi=8.d0*atan(1.d0)
13  w=1.d0
14  dphi=twopi*f0/12000.d0
15  wstep=cmplx(cos(dphi),sin(dphi))
16  do i=1,jz
17     w=w*wstep
18     w4=w
19     cb(i)=w4*ca(i)
20  enddo
21
22  return
23end subroutine tweak1
24