function data = qfft(data);
% QFFT One-sided Fourier transform of time domain data
%
% QFFT computes the one-sided Fourier transform of time domain data similar to
% the output produced by QCONDITION and QSCANCONDITION.  The resulting one-sided
% frequency domain data are assumed to extend from zero frequency to the Nyquist
% frequency.  As a result, time domain data of length N corresponds to frequency
% domain data of length N / 2 + 1.
%
% QFFT can be used as a placebo replacement for QCONDITION.
%
% usage:
%
% frequencyDomainData = qfft(timeDomainData);
%
%   timeDomainData        cell array of time domain data
%
%   frequencyDomainData   cell array of one-sided frequency domain data
%
% See also QIFFT, QCONDITION, and QSCANCONDITION.

% Shourov K. Chatterji
% shourov@ligo.mit.edu

% $Id: qfft.m,v 1.1 2006/10/05 17:00:14 shourov Exp $

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                        process command line arguments                        %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% check for sufficient command line arguments
error(nargchk(1, 1, nargin));

% force cell array of data
if ~iscell(data),
  data = mat2cell(data, size(data, 1), size(data, 2));
end

% force one dimensional cell array
data = data(:);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                       validate command line arguments                        %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% determine number of channels
numberOfChannels = length(data);

% force row vectors
for channelNumber = 1 : numberOfChannels,
  data{channelNumber} = data{channelNumber}(:).';
end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                            fast fourier transform                            %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% inverse fourier transform
for channelNumber = 1 : numberOfChannels,
  data{channelNumber} = fft(data{channelNumber});
  data{channelNumber} = ...
      data{channelNumber}(1 : length(data{channelNumber}) / 2 + 1);
end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                    return                                    %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% return to calling function
return;