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ltpda_polydetrend

PURPOSE ^

LTPDA_POLYDETREND detrends the input analysis object using a polynomial

SYNOPSIS ^

function bo = ltpda_polydetrend(varargin)

DESCRIPTION ^

 LTPDA_POLYDETREND detrends the input analysis object using a polynomial
 of degree N.
 
 >> b = ltpda_polydetrend(a1,a2,a3,..., pl)
 
 Inputs:
   aN  - a list of analysis objects
   pl  - a parameter list
 
 Outputs:
   b - array of analysis objects
 
 If the last input argument is a parameter list (plist) it is used. The
 following parameters are recognised.
 
 Parameters:
   'N' - degree of polynomial [default: 3]
 
 M Hewitson, A Monsky 01-03-07
 
 $Id: ltpda_polydetrend.html,v 1.1 2007/06/08 14:15:11 hewitson Exp $

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function bo = ltpda_polydetrend(varargin)
0002 
0003 % LTPDA_POLYDETREND detrends the input analysis object using a polynomial
0004 % of degree N.
0005 %
0006 % >> b = ltpda_polydetrend(a1,a2,a3,..., pl)
0007 %
0008 % Inputs:
0009 %   aN  - a list of analysis objects
0010 %   pl  - a parameter list
0011 %
0012 % Outputs:
0013 %   b - array of analysis objects
0014 %
0015 % If the last input argument is a parameter list (plist) it is used. The
0016 % following parameters are recognised.
0017 %
0018 % Parameters:
0019 %   'N' - degree of polynomial [default: 3]
0020 %
0021 % M Hewitson, A Monsky 01-03-07
0022 %
0023 % $Id: ltpda_polydetrend.html,v 1.1 2007/06/08 14:15:11 hewitson Exp $
0024 %
0025 
0026 % capture input variable names
0027 invars = {};
0028 for j=1:nargin
0029   invars = [invars cellstr(inputname(j))];
0030 end
0031 
0032 ALGONAME = mfilename;
0033 VERSION  = '$Id: ltpda_polydetrend.html,v 1.1 2007/06/08 14:15:11 hewitson Exp $';
0034 
0035 % Look at inputs
0036 if nargin < 1
0037   error('### Incorrect number of inputs.')
0038 end
0039 
0040 args = varargin;
0041 if isa(args{end}, 'plist')
0042   pl = args{end};
0043   args = args(1:end-1);
0044 else
0045   pl = plist();
0046 end
0047 na = length(args);
0048 
0049 % Check input objects
0050 for j=1:na
0051   if ~isa(args{j}, 'ao')
0052     error('### LTPDA_COHERE only works with analysis objects.');
0053   end
0054 end
0055 
0056 % Initialise output
0057 bo = [];
0058 
0059 % Unpack parameter list
0060 plo = plist();
0061 N = find(pl, 'N');
0062 if isempty(N)
0063   N = 1;
0064   warning(sprintf('!!! Using default polynomial degree %d', N))
0065 end
0066 plo = append(plo, param('N', N));
0067 
0068 % Loop over analysis objects
0069 for i=1:na
0070   
0071   % get data out
0072   a = args{i};
0073   d = a.data;
0074   dinfo = whos('d');
0075   if ~isa(d, 'tsdata')
0076     error('### I only work with time-series at the moment.');
0077   end
0078   if ~isreal(d.x)
0079     error('### I only work with real time-series at the moment.');
0080   end
0081   
0082 %   % fit polynomial
0083 %   p = polyfit(d.t, d.x, N);
0084 %   plo = append(plo, param('coefficients', p));
0085 %
0086 %   % make polynomial series
0087 %   py = polyval(p, d.t);
0088 %
0089 %   % detrend
0090 %   y = d.x - py;
0091 
0092   y = polydetrend(d.x, N);
0093 
0094   % Make output analysis object
0095   nameStr = sprintf('poly_detrend(%s)', d.name);
0096   
0097   % create new output data
0098   data = tsdata(y, d.fs);
0099   data = set(data, 'name', nameStr);
0100   data = set(data, 'xunits', d.xunits);
0101   data = set(data, 'yunits', d.yunits);
0102 
0103   % create new output history
0104   h = history(ALGONAME, VERSION, plo, a.hist);
0105   h = set(h, 'invars', invars);
0106 
0107   % make output analysis object
0108   b = ao(data, h);
0109 
0110   % set name
0111   % name for this object
0112   if isempty(invars{i})
0113     n1 = a.name;
0114   else
0115     n1 = invars{i};
0116   end
0117 
0118   nameStr = sprintf('poly_detrend(%s)', n1);
0119   b = set(b, 'name', nameStr);
0120 
0121   % Add to output array
0122   bo = [bo b];
0123   
0124 end
0125 
0126 % END

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