1subroutine twkfreq1(ca,npts,fsample,a,cb) 2 3 complex ca(npts) 4 complex cb(npts) 5 complex w,wstep 6 real a(5) 7 data twopi/6.283185307/ 8 9! Mix the complex signal 10 w=1.0 11 wstep=1.0 12 x0=0.5*(npts+1) 13 s=2.0/npts 14 do i=1,npts 15 x=s*(i-x0) 16 p2=1.5*x*x - 0.5 17 p3=2.5*(x**3) - 1.5*x 18 p4=4.375*(x**4) - 3.75*(x**2) + 0.375 19 dphi=(a(1) + x*a(2) + p2*a(3) + p3*a(4) + p4*a(5)) * (twopi/fsample) 20 wstep=cmplx(cos(dphi),sin(dphi)) 21 w=w*wstep 22 cb(i)=w*ca(i) 23 enddo 24 25 return 26end subroutine twkfreq1 27