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annotate m-toolbox/classes/@ao/ifft_core.m @ 43:bc767aaa99a8

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CVS Update
author Daniele Nicolodi <nicolodi@science.unitn.it>
date Tue, 06 Dec 2011 11:09:25 +0100
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Daniele Nicolodi <nicolodi@science.unitn.it>
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1 % IFFT_CORE Simple core method which computes the ifft.
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2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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3 %
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4 % DESCRIPTION: Simple core method which computes the ifft.
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5 %
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6 % CALL: ao = ifft_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 ifft type
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10 % 'symmetric'
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11 % 'nonsymmetric'
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12 %
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13 % VERSION: $Id: ifft_core.m,v 1.6 2011/02/14 19:33:35 ingo Exp $
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14 %
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15 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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16 function bs = ifft_core(bs, type)
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17
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18 switch class(bs.data)
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19 case {'fsdata'}
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20 fs = bs.data.fs;
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21 % check fft type
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22 if any((bs.data.x)<0) % two sided fft
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23 utils.helper.msg(utils.const.msg.PROC1, 'two sided fft');
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24 y = ifftshift(bs.data.y);
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25 else
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26 % get minimum frequency step
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27 df = bs.data.x(end)-bs.data.x(end-1);
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28 if abs(((fs-df)-bs.data.x(end)))<eps % plain fft
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29 utils.helper.msg(utils.const.msg.PROC1, 'plain fft');
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30 y = bs.data.y;
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31 elseif abs((bs.data.x(end)-fs/2))<eps % onesided fft even nfft
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32 utils.helper.msg(utils.const.msg.PROC1, 'one sided fft even nfft');
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33 y1 = bs.data.y(1:end);
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34 y2 = conj(bs.data.y(end-1:-1:2));
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35 if size(y1,1)==1 % raw
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36 y = [y1 y2];
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37 else
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38 y = [y1;y2];
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39 end
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40 else % onesided fft odd nfft
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41 utils.helper.msg(utils.const.msg.PROC1, 'one sided fft odd nfft');
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42 y1 = bs.data.y(1:end);
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43 y2 = conj(bs.data.y(end:-1:2));
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44 if size(y1,1)==1 % raw
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45 y = [y1 y2];
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46 else
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47 y = [y1;y2];
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48 end
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49 end
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50 end
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51
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52 y = ifft(y, type);
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53 % Keep the data shape if the input AO
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54 if size(bs.data.y, 1) == 1
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55 y = y.';
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56 end
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57
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58 % make a new tsdata object
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59 fsd = tsdata(y, fs);
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60 fsd.setXunits('s');
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61 fsd.setYunits(bs.yunits);
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62
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63 % Set data
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64 bs.data = fsd;
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65 % clear errors
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66 bs.clearErrors;
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67
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68 case {'tsdata', 'cdata', 'xydata'}
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69 error('### I don''t work for time-series, constant or x/y data.');
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70 otherwise
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71 error('### unknown data type.')
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72 end
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73
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74
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75 end
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76
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