27 lines
540 B
Plaintext
27 lines
540 B
Plaintext
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subroutine twkfreq(c3,c4,npts,fsample,a)
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complex c3(npts)
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complex c4(npts)
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complex w,wstep
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real a(3)
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data twopi/6.283185307/
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! Mix the complex signal
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w=1.0
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wstep=1.0
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x0=0.5*(npts+1)
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s=2.0/npts
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do i=1,npts
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x=s*(i-x0)
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p2=1.5*x*x - 0.5
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! p3=2.5*(x**3) - 1.5*x
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! p4=4.375*(x**4) - 3.75*(x**2) + 0.375
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dphi=(a(1) + x*a(2) + p2*a(3)) * (twopi/fsample)
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wstep=cmplx(cos(dphi),sin(dphi))
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w=w*wstep
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c4(i)=w*c3(i)
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enddo
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return
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end subroutine twkfreq
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