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filtfilt

PURPOSE ^

FILTFILT overides the filtfilt function for analysis objects.

SYNOPSIS ^

function varargout = filtfilt(varargin)

DESCRIPTION ^

 FILTFILT overides the filtfilt function for analysis objects.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 DESCRIPTION: FILTFILT overides the filtfilt function for analysis objects.
              Applies the input digital IIR filter to the input analysis object
              forwards and backwards. If the input analysis object contains a
              time-series (tsdata) then the filter is applied using the normal
              recursion algorithm. The output analysis object contains a tsdata
              object.

              If the input analysis object contains a frequency-series (fsdata)
              then the response of the filter is computed and then multiplied
              with the input frequency series. The output analysis object
              contains a frequency series.

 CALL:        >> [b, filt] = filtfilt(a,pl)
              >> b = filtfilt(a,pl)

 INPUTS:      pl   - a parameter list
              a    - input analysis object

 OUTPUTS:     filt - a copy of the input filter object with the
                     history values filled in.
              b    - output analysis object containing the filtered data.

 PARAMETERS:  filter - the filter object to use to filter the data

 REMARK:      Uses ltpda_filtfilt() to do the filtering.

 VERSION:     $Id: filtfilt.m,v 1.13 2007/11/26 14:48:13 ingo Exp $

 The following call returns a parameter list object that contains the
 default parameter values:

 >> pl = filtfilt(ao, 'Params')

 HISTORY: 11-02-07 M Hewitson
             Creation

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SUBFUNCTIONS ^

SOURCE CODE ^

0001 function varargout = filtfilt(varargin)
0002 % FILTFILT overides the filtfilt function for analysis objects.
0003 %
0004 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0005 %
0006 % DESCRIPTION: FILTFILT overides the filtfilt function for analysis objects.
0007 %              Applies the input digital IIR filter to the input analysis object
0008 %              forwards and backwards. If the input analysis object contains a
0009 %              time-series (tsdata) then the filter is applied using the normal
0010 %              recursion algorithm. The output analysis object contains a tsdata
0011 %              object.
0012 %
0013 %              If the input analysis object contains a frequency-series (fsdata)
0014 %              then the response of the filter is computed and then multiplied
0015 %              with the input frequency series. The output analysis object
0016 %              contains a frequency series.
0017 %
0018 % CALL:        >> [b, filt] = filtfilt(a,pl)
0019 %              >> b = filtfilt(a,pl)
0020 %
0021 % INPUTS:      pl   - a parameter list
0022 %              a    - input analysis object
0023 %
0024 % OUTPUTS:     filt - a copy of the input filter object with the
0025 %                     history values filled in.
0026 %              b    - output analysis object containing the filtered data.
0027 %
0028 % PARAMETERS:  filter - the filter object to use to filter the data
0029 %
0030 % REMARK:      Uses ltpda_filtfilt() to do the filtering.
0031 %
0032 % VERSION:     $Id: filtfilt.m,v 1.13 2007/11/26 14:48:13 ingo Exp $
0033 %
0034 % The following call returns a parameter list object that contains the
0035 % default parameter values:
0036 %
0037 % >> pl = filtfilt(ao, 'Params')
0038 %
0039 % HISTORY: 11-02-07 M Hewitson
0040 %             Creation
0041 %
0042 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0043 
0044 ALGONAME = mfilename;
0045 VERSION  = '$Id: filtfilt.m,v 1.13 2007/11/26 14:48:13 ingo Exp $';
0046 bo       = [];
0047 filt     = [];
0048 
0049 %% Check if this is a call for parameters
0050 if nargin == 2
0051   if isa(varargin{1}, 'ao') && ischar(varargin{2})
0052     in = char(varargin{2});
0053     if strcmp(in, 'Params')
0054       varargout{1} = getDefaultPL();
0055       return
0056     elseif strcmp(in, 'Version')
0057       varargout{1} = VERSION;
0058       return
0059     end
0060   end
0061 end
0062 
0063 % Collect input ao's, plist's and ao variable names
0064 in_names = {};
0065 for ii = 1:nargin
0066   in_names{end+1} = inputname(ii);
0067 
0068   if isa(varargin{ii}, 'miir')
0069     filt = varargin{ii};
0070   end
0071 end
0072 
0073 [as, ps, invars] = collect_inputs(varargin, in_names);
0074 
0075 if isa(ps, 'plist')
0076   pl = combine(ps);
0077 else
0078   pl = plist();
0079 end
0080 
0081 if isempty(filt)
0082   filt = find(pl, 'filter');
0083 end
0084 
0085 % check inputs
0086 if ~isa(filt, 'miir')
0087   error('### the first input should be an miir object.');
0088 end
0089 if ~isa(as, 'ao')
0090   error('### second input should be an analysis object.');
0091 end
0092 
0093 for ii=1:numel(as)
0094 
0095   % get input data
0096   a = as(ii);
0097   d = a.data;
0098 
0099   %--------- Time-series filter
0100   %
0101   if isa(d, 'tsdata')
0102 
0103     % get input data
0104     y  = d.y;
0105     fs = d.fs;
0106     if fs ~= get(filt, 'fs')
0107       warning('!!! Filter is designed for a different sample rate of data.');
0108       % Adjust/redesign if this is a standard filter
0109       filt = redesign(filt, fs);
0110     end
0111 
0112     % get filter coeffs
0113     ac = get(filt,'a');
0114     bc = get(filt,'b');
0115 
0116     % apply filter
0117     y = filtfilt(ac, bc, y);
0118     %   [fstruct, y] = ltpda_filtfilt(struct(filt), d.y, length(d.y));
0119     % consolodate this structure with miir class before converting.
0120     %   filt = set(filt, 'histin', fstruct.histin);
0121     %   filt = set(filt, 'histout', fstruct.histout);
0122 
0123     %----- Create output analysis object
0124     % make a new tsdata object
0125     ts = tsdata(d.x, y);
0126     ts = set(ts, 'name', sprintf('filtfilt %s with %s', d.name, get(filt,'name')));
0127     ts = set(ts, 'xunits', d.xunits);
0128     ts = set(ts, 'yunits', d.yunits);
0129     ts = set(ts, 't0', d.t0);
0130 
0131     % make a new history object
0132     pl = plist();
0133     pl = append(pl, param('filter', filt));
0134     h = history(ALGONAME, VERSION, pl, a.hist);
0135     h = set(h, 'invars', cellstr(invars{ii}));
0136 
0137     % make output analysis object
0138     bs = ao(ts, h);
0139     % name for this object
0140     bs = setnh(bs, 'name', sprintf('%s(%s)', get(filt,'name'), invars{ii}));
0141 
0142     bo = [bo bs];
0143 
0144     %--------- Frequency-series filter
0145     %
0146   elseif isa(d, 'fsdata')
0147     error('### I don''t work yet. Please code me up.');
0148 
0149   else
0150     error('### unknown data type.');
0151   end
0152 
0153 end
0154 
0155 % Reshape the ouput to the same size of the input
0156 bo = reshape(bo, size(as));
0157 
0158 if nargout == 1
0159   varargout{1} = bo;
0160 elseif nargout == 2
0161   varargout{1} = bo;
0162   varargout{2} = filt;
0163 else
0164   error('### wrong number of output arguments.');
0165 end
0166 
0167 
0168 %% Get default params
0169 function pl_default = getDefaultPL()
0170 
0171   pl_default = plist(param('filter',  ''));

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