function [q,w]=cut_and_zero(qstart_time,wstart_time,end_time,q,w)

if isnan(end_time) 
    end_time = round(length(q.time) / q.freq);
end

% Make time series equally long
if q.time(end)>w.time(end)
    qend_time=qstart_time+(end_time-wstart_time);
    wend_time=end_time;
else
    wend_time=wstart_time+(end_time-qstart_time);
    qend_time=end_time;
end
iqs=round(qstart_time*q.freq);  
iqe=round(qend_time*q.freq);  

iws=round(wstart_time*w.freq);      
iwe=round(wend_time*w.freq);

% Can be inaccuracy in wave data sampling end time, causing error of 
% exceeding matrix dimensions. Then remove one second at end in both data sets.
if iwe>length(w.time) 
    iwe=iwe - 1*w.freq;
    iqe=iqe - 1*q.freq;
end

% Zero to start at t=0s
q.time=q.time(iqs:iqe)-q.time(iqs); 
w.time=w.time(iws:iwe)-w.time(iws);

% Zero data around mean
q.data6D=q.data6D(iqs:iqe,:)-mean(q.data6D(iqs:iqe,:));
w.data=w.data(iws:iwe,:)-mean(w.data(iws:iwe,:));