function [wlp,jd]=getvlp(cdf,start,stop);
%GETVLP gets low-passed velocity time series from cdf file(s)
%  USAGE 
%     [wlp,jd]=getvlp(cdf,start,stop);
%     or
%     [wlp,jd]=getvlp(cdf);
% 
%  where: cdf = string containing the name of the cdf file, or a 
%               string array containing the names of multiple cdf files, i.e.
%               cdf=['cdf_file1.cdf'
%                    'cdf_file2.cdf'
%                    'junk.cdf     '];
%         start = [yyyy mm dd hh mi sc];
%         stop  = [yyyy mm dd hh mi sc];
%
%    if start and stop are missing, then the series overlapping in time are 
%     returned.  U and V must be called 'east' and 'north' in cdf file.
%
%         jd = julian day 
if nargin==1,
  [w,jd]=getv(cdf);
else
  [w,jd]=getv(cdf,start,stop);
end
wlp=plfilt(w);
[m,n]=size(wlp);
jd=jd(34:34+m-1);
