% function [T,X]=my_filter(t,x,l,o);
%
% Uses the butterworth filter to filter the data. 
% 
% t   : time vector
% x   : data vector or matrix
% l   : l=length of filter 
% o   : order of filter
%
% T   : new time vector (end values removed)
% X   : filtered vector or matrix
% made by Tore Furevik, Geophysical Institute, University of Bergen.
% email: tore@gfi.uib.no                             Date 18/9-1997.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [T,X]=my_filter(t,x,l,o);
[b,a]=butter(o,2/l); [I,J]=size(x);
X=filtfilt(b,a,x);
T=0.5*(t(1:length(t)+1-l)+t(l:length(t)));
c=l+1;
if (min(I,J)==1) 
  X=0.5*(X(floor(c/2):length(X)+1-ceil(c/2))+...
         X(ceil(c/2):length(X)+1-floor(c/2)));
else   
  X=0.5*(X(floor(c/2):I+1-ceil(c/2),:)+...
         X(ceil(c/2):I+1-floor(c/2),:));
end;