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annotate m-toolbox/classes/@ao/fft_core.m @ 45:a59cdb8aaf31 database-connection-manager

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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Tue, 06 Dec 2011 19:07:22 +0100
parents f0afece42f48
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Daniele Nicolodi <nicolodi@science.unitn.it>
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1 % FFT_CORE Simple core method which computes the fft.
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2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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3 %
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4 % DESCRIPTION: Simple core method which computes the fft.
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5 %
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6 % CALL: ao = fft_core(ao, type)
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7 %
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8 % INPUTS: ao: Single input analysis object
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9 % type: The fft type
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10 % 'plain' - complete non-symmetric
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11 % 'one' - from zero to Nyquist
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12 % 'two' - complete symmetric
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13 %
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14 % VERSION: $Id: fft_core.m,v 1.7 2011/02/04 17:42:29 luigi Exp $
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15 %
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16 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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17 function bs = fft_core(bs, type)
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18
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19 % Which data type do we have
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20 switch class(bs.data)
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21 case {'tsdata', 'cdata', 'xydata'}
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22 % Check we have a sample rate
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23 if strcmp(class(bs.data), 'tsdata')
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24 fs = bs.data.fs;
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25 fmin = 0;
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26 else
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27 warning('!!! Data has no sample rate: setting to %g', 2+length(bs.data.y));
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28 fs = 2+length(bs.data.y);
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29 fmin = 1;
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30 end
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31 % make FFT of data
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32 xunits = 'Hz';
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33 nfft = length(bs.data.y);
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34 ft = fft(bs.data.y);
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35 f = utils.math.getfftfreq(nfft,fs,type);
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36 switch lower(type)
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37 case 'plain' % get true matlab fft
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38 f = reshape(f,size(ft));
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39 case 'one'
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40 ft = ft(1:floor(nfft/2)+1);
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41 f = reshape(f,size(ft));
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42 case 'two'
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43 if size(ft, 1) == 1
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44 ft = fftshift(ft);
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45 else
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46 ft = fftshift(ft);
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47 if rem(nfft,2) % odd number of data
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48 f = f.';
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49 else % even number of data
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50 f = f.';
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51 end
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52 end
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53 otherwise
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54 error('### unknown fft type.');
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55 end
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56 % Make new fsdata object
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57 fsd = fsdata(f, ft, fs);
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58 fsd.setXunits(xunits);
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59 fsd.setYunits(bs.data.yunits);
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60 % make output analysis object
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61 bs.data = fsd;
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62 % clear errors
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63 bs.clearErrors;
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64
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65 otherwise
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66 error('### You can only fft tsdata, cdata, or xydata AOs.');
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67 end
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68
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69 end
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70
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