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Re: FFT phase? [message #82915 is a reply to message #82911]

Thu, 24 January 2013 18:11

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

On Thursday, January 24, 2013 12:28:02 PM UTC-5, xqin...@gmail.com wrote:
> Hi,
>
>
>
> just use FFT(y). For example, y=A*cos(x+B), C=fft(y). I think atan(C,/phase) should equal to B, but the return reslut is not. How to obtain A and B from complex C?

It is correct. Example:
x = 2*!dpi*2*dindgen(16)/16 ;; Angle in radians
y = 0.7*cos(x + 1.6000)
c = fft(y,-1)
print, atan(c[2],/phase)
==> 1.6000

Craig

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[Message index]

		Re: FFT phase? By: Craig Markwardt on Fri, 25 January 2013 13:48
		Re: FFT phase? By: Yngvar Larsen on Fri, 25 January 2013 05:18
		Re: FFT phase? By: xqinshan on Thu, 24 January 2013 22:49
		Re: FFT phase? By: Craig Markwardt on Thu, 24 January 2013 18:11

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