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dft

PURPOSE ^

DFT computes the DFT of the input time-series at the requested frequencies.

SYNOPSIS ^

function varargout = dft(varargin)

DESCRIPTION ^

 DFT computes the DFT of the input time-series at the requested frequencies.
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 DESCRIPTION: DFT computes the DFT of the input time-series at the requested
              frequencies.

 CALL:        b = dft(a, pl)

 PARAMETERS:
              'f'  - vector of frequencies at which to compute the DFT.
                     [default: linspace(1/ndata,fs/2,ndata/2+1)]

 M-FILE INFO: Get information about this methods by calling
              >> ao.getInfo('dft')

              Get information about a specified set-plist by calling:
              >> ao.getInfo('dft', 'None')

 VERSION:     $Id: dft.m,v 1.10 2008/08/15 11:45:18 ingo Exp $

 HISTORY:     25-04-08 M Hewitson
                 Creation

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CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SUBFUNCTIONS ^

SOURCE CODE ^

0001 % DFT computes the DFT of the input time-series at the requested frequencies.
0002 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0003 %
0004 % DESCRIPTION: DFT computes the DFT of the input time-series at the requested
0005 %              frequencies.
0006 %
0007 % CALL:        b = dft(a, pl)
0008 %
0009 % PARAMETERS:
0010 %              'f'  - vector of frequencies at which to compute the DFT.
0011 %                     [default: linspace(1/ndata,fs/2,ndata/2+1)]
0012 %
0013 % M-FILE INFO: Get information about this methods by calling
0014 %              >> ao.getInfo('dft')
0015 %
0016 %              Get information about a specified set-plist by calling:
0017 %              >> ao.getInfo('dft', 'None')
0018 %
0019 % VERSION:     $Id: dft.m,v 1.10 2008/08/15 11:45:18 ingo Exp $
0020 %
0021 % HISTORY:     25-04-08 M Hewitson
0022 %                 Creation
0023 %
0024 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0025 
0026 function varargout = dft(varargin)
0027 
0028   % Check if this is a call for parameters
0029   if utils.helper.isinfocall(varargin{:})
0030     varargout{1} = getInfo(varargin{3});
0031     return
0032   end
0033 
0034   import utils.const.*
0035   utils.helper.msg(msg.MNAME, 'running %s/%s', mfilename('class'), mfilename);
0036   
0037   % Collect input variable names
0038   in_names = cell(size(varargin));
0039   for ii = 1:nargin,in_names{ii} = inputname(ii);end
0040 
0041   % Collect all AOs
0042   [as, ao_invars] = utils.helper.collect_objects(varargin(:), 'ao', in_names);
0043   [pl, pl_invars] = utils.helper.collect_objects(varargin(:), 'plist', in_names);
0044 
0045   % Make copies or handles to inputs
0046   bs = copy(as, nargout);
0047 
0048   % Combine plists
0049   pl = combine(pl, getDefaultPlist);
0050 
0051   % Extract necessary parameters
0052   f = find(pl, 'f');
0053 
0054   % Loop over input AOs
0055   for j=1:length(bs)
0056     if ~isa(bs(j).data, 'tsdata')
0057       warning('!!! The DFT can only be computed on input time-series. Skipping AO %s', ao_invars{j});
0058     else
0059       % Compute f if necessary
0060       if f < 0
0061         f = linspace(0, bs(j).data.fs/2, length(bs(j).data.y)/2+1);
0062       end
0063 
0064       % Compute DFT
0065       fs  = bs(j).data.fs;
0066       N   = length(bs(j).data.y);
0067       J   = -2*pi*1i.*[0:N-1]/fs;
0068       dft = zeros(size(f));
0069       for kk = 1:length(f)
0070         dft(kk) = exp(f(kk)*J)*bs(j).data.y.';
0071       end
0072 
0073       % Make output fsdata AO
0074       yunits = bs(j).data.yunits;
0075       bs(j).data = fsdata(f, dft, bs(j).data.fs);
0076       bs(j).setXunits('Hz', 'internal');
0077       bs(j).setYunits(yunits/sym('Hz'), 'internal');
0078       % Set name
0079       bs(j).setName(sprintf('dft(%s)', ao_invars{j}), 'internal');
0080       % Add history
0081       bs(j).addHistory(getInfo, pl, ao_invars(j), bs(j).hist);
0082     end
0083   end
0084 
0085   % Set outputs
0086   if nargout > 0
0087     varargout{1} = bs;
0088   end
0089 end
0090 
0091 %--------------------------------------------------------------------------
0092 % Get Info Object
0093 %--------------------------------------------------------------------------
0094 function ii = getInfo(varargin)
0095   if nargin == 1 && strcmpi(varargin{1}, 'None')
0096     sets = {};
0097     pls  = [];
0098   else
0099     sets = {'Default'};
0100     pls  = getDefaultPlist;
0101   end
0102   % Build info object
0103   ii = minfo(mfilename, 'ao', '', 'Signal Processing', '$Id: dft.m,v 1.10 2008/08/15 11:45:18 ingo Exp $', sets, pls);
0104 end
0105 
0106 %--------------------------------------------------------------------------
0107 % Get Default Plist
0108 %--------------------------------------------------------------------------
0109 function pl = getDefaultPlist()
0110   pl = plist('f', -1);
0111 end
0112 
0113

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