function Ynorm=eventsnormalize(Y,DF,np)
%EVENTSNORMALIZE multi periods array normalizing
%   YNORM = EVENTSNORMALIZE(Y,DF,NP) normalize the columns of
%   the matrix/array Y in NP points between the time
%   intervals defined by the matrix DF:
%   
%   DF=
%	    F1beg,F1end
%	    F2beg,F2end
%		...
%	    Fnbeg,Fnend
%
%   Use carefully this function because no anti aliasing
%   filter is applied!!!
%
%   See also eventscycle
%   Author(s): F. Patanč, 2000

c=size(Y,2);
intervals=size(DF,1);
if isempty(DF)|np<=1|isempty(Y)
    Ynorm=[];
    return
else
    Ynorm=zeros(np*intervals,c);
    for i=1:intervals
        l=DF(i,2)-DF(i,1)+1;
        if l>1.5*np
            Ynorm((i-1)*np+1:i*np,:)=resample(Y( DF(i,1):DF(i,2),: ),np,l,0);
        else
            Ynorm((i-1)*np+1:i*np,:)=upresample(Y( DF(i,1):DF(i,2),: ),np,l,2);
        end
    end
end