Calculation FFT...
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From: alex65111 on 19 May 2010 16:07 >Reconstitute the original samples with IFFT(Y) and go from there. > >Jerry >-- >"I view the progress of science as ... the slow erosion of the tendency > to dichotomize." --Barbara Smuts, U. Mich. >??????????????????????????????????????????????????????????????????????? > The problem to receive result without reconstruction, operating only with spectral samples.
From: alex65111 on 19 May 2010 16:16 It turns out so that at the decision of one stage of a problem to have to count FFT the large size, and at the second stage it is required on the same data FFT of the smaller size. Accordingly it would be desirable to count not anew FFT, and to use result from the first stage.
From: Jerry Avins on 19 May 2010 17:32 On 5/19/2010 4:16 PM, alex65111 wrote: > It turns out so that at the decision of one stage of a problem to have to > count FFT the large size, and at the second stage it is required on the > same data FFT of the smaller size. Accordingly it would be desirable to > count not anew FFT, and to use result from the first stage. As far as I know, it doesn't work that way. Jerry -- "I view the progress of science as ... the slow erosion of the tendency to dichotomize." --Barbara Smuts, U. Mich. �����������������������������������������������������������������������
From: alex65111 on 20 May 2010 02:03 >If you are looking for something with "wider" bins you need to do >something else. > >If you are only interested in power, you can form sums of the powers >of adjacent bins. > >The more you can narrow down the application of the 256 values, the >more likely there is to be a simple solution or approximation. So, if >you want something else, what are you going to do with it? > >Dale B. Dalrymple Yes, it is necessary to look with "wider" bins and only power. It seems that "sums of the powers of adjacent bins" this that that is necessary.
From: Jerry Avins on 20 May 2010 15:22
On 5/20/2010 2:03 AM, alex65111 wrote: >> If you are looking for something with "wider" bins you need to do >> something else. >> >> If you are only interested in power, you can form sums of the powers >> of adjacent bins. >> >> The more you can narrow down the application of the 256 values, the >> more likely there is to be a simple solution or approximation. So, if >> you want something else, what are you going to do with it? >> >> Dale B. Dalrymple > > Yes, it is necessary to look with "wider" bins and only power. > It seems that "sums of the powers of adjacent bins" this that that is > necessary. Your original question was misleading, then. "Power only" does not duplicate the result of an FFT. You get better answers when you ask what you really want to know. Jerry -- "I view the progress of science as ... the slow erosion of the tendency to dichotomize." --Barbara Smuts, U. Mich. ����������������������������������������������������������������������� |