function ufilt=plfilt(u)
%              ufilt=plfilt(u)
%           loads and uses pl33 filter
%			cuts off 33 hours at beginning and end
load pl33
ufilt=conv(u,pl33);
ufilt=ufilt(34:length(u)+33);
ufilt(1:33)=ones(1:33)*nan;
ufilt(length(ufilt)-32:length(ufilt))=ufilt(1:33);
