idamnjanovic@1: function [y,dc] = remove_dc(x,columns)
idamnjanovic@1: %REMOVE_DC Remove DC channel from signals.
idamnjanovic@1: %   [Y,DC] = REMOVE_DC(X) removes the DC channel (i.e. the mean) from the
idamnjanovic@1: %   specified (possibly multi-dimensional) signal X. Y is the DC-free
idamnjanovic@1: %   signal and is the same size as X. DC is a scalar containing the mean of
idamnjanovic@1: %   the signal X.
idamnjanovic@1: %
idamnjanovic@1: %   [Y,DC] = REMOVE_DC(X,'columns') where X is a 2D matrix, treats the
idamnjanovic@1: %   columns of X as a set of 1D signals, removing the DC channel from each
idamnjanovic@1: %   one individually. Y is the same size as X and contains the DC-free
idamnjanovic@1: %   signals. DC is a row vector of length size(X,2) containing the means of
idamnjanovic@1: %   the signals in X.
idamnjanovic@1: %
idamnjanovic@1: %   See also ADD_DC.
idamnjanovic@1: 
idamnjanovic@1: 
idamnjanovic@1: if (nargin==2 && strcmpi(columns,'columns')), columns = 1;
idamnjanovic@1: else columns = 0;
idamnjanovic@1: end
idamnjanovic@1: 
idamnjanovic@1: if (columns)
idamnjanovic@1:   dc = mean(x);
idamnjanovic@1:   y = addtocols(x,-dc);
idamnjanovic@1: else
idamnjanovic@1:   if (ndims(x)==2)  % temporary, will remove in future
idamnjanovic@1:     warning('Treating 2D matrix X as a single signal and not each column individually');
idamnjanovic@1:   end
idamnjanovic@1:   dc = mean(x(:));
idamnjanovic@1:   y = x-dc;
idamnjanovic@1: end
idamnjanovic@1: