function Y=pulsetrain(x,Tx)
minx=min(x);
maxx=max(x);
Nmin=sign(minx)*ceil(abs(minx/Tx));
Nmax=sign(maxx)*ceil(abs(maxx/Tx));
s=size(x);
Y=zeros(s);
Tx2=0.0001;
for t=Nmin:1:Nmax,
   xdel=Tx*t;
   rectx=0.5*(sign((x+Tx2)-xdel)-sign((x-Tx2)-xdel));
   Y=Y+rectx;
end