Mercurial > hg > ltpda
comparison m-toolbox/classes/@ao/fft_core.m @ 0:f0afece42f48
Import.
| author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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| date | Wed, 23 Nov 2011 19:22:13 +0100 |
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| -1:000000000000 | 0:f0afece42f48 |
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| 1 % FFT_CORE Simple core method which computes the fft. | |
| 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | |
| 3 % | |
| 4 % DESCRIPTION: Simple core method which computes the fft. | |
| 5 % | |
| 6 % CALL: ao = fft_core(ao, type) | |
| 7 % | |
| 8 % INPUTS: ao: Single input analysis object | |
| 9 % type: The fft type | |
| 10 % 'plain' - complete non-symmetric | |
| 11 % 'one' - from zero to Nyquist | |
| 12 % 'two' - complete symmetric | |
| 13 % | |
| 14 % VERSION: $Id: fft_core.m,v 1.7 2011/02/04 17:42:29 luigi Exp $ | |
| 15 % | |
| 16 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | |
| 17 function bs = fft_core(bs, type) | |
| 18 | |
| 19 % Which data type do we have | |
| 20 switch class(bs.data) | |
| 21 case {'tsdata', 'cdata', 'xydata'} | |
| 22 % Check we have a sample rate | |
| 23 if strcmp(class(bs.data), 'tsdata') | |
| 24 fs = bs.data.fs; | |
| 25 fmin = 0; | |
| 26 else | |
| 27 warning('!!! Data has no sample rate: setting to %g', 2+length(bs.data.y)); | |
| 28 fs = 2+length(bs.data.y); | |
| 29 fmin = 1; | |
| 30 end | |
| 31 % make FFT of data | |
| 32 xunits = 'Hz'; | |
| 33 nfft = length(bs.data.y); | |
| 34 ft = fft(bs.data.y); | |
| 35 f = utils.math.getfftfreq(nfft,fs,type); | |
| 36 switch lower(type) | |
| 37 case 'plain' % get true matlab fft | |
| 38 f = reshape(f,size(ft)); | |
| 39 case 'one' | |
| 40 ft = ft(1:floor(nfft/2)+1); | |
| 41 f = reshape(f,size(ft)); | |
| 42 case 'two' | |
| 43 if size(ft, 1) == 1 | |
| 44 ft = fftshift(ft); | |
| 45 else | |
| 46 ft = fftshift(ft); | |
| 47 if rem(nfft,2) % odd number of data | |
| 48 f = f.'; | |
| 49 else % even number of data | |
| 50 f = f.'; | |
| 51 end | |
| 52 end | |
| 53 otherwise | |
| 54 error('### unknown fft type.'); | |
| 55 end | |
| 56 % Make new fsdata object | |
| 57 fsd = fsdata(f, ft, fs); | |
| 58 fsd.setXunits(xunits); | |
| 59 fsd.setYunits(bs.data.yunits); | |
| 60 % make output analysis object | |
| 61 bs.data = fsd; | |
| 62 % clear errors | |
| 63 bs.clearErrors; | |
| 64 | |
| 65 otherwise | |
| 66 error('### You can only fft tsdata, cdata, or xydata AOs.'); | |
| 67 end | |
| 68 | |
| 69 end | |
| 70 | |
| 71 | |
| 72 | |
| 73 |