function w=shiftl(v,n)
%SHIFTL	 W=SHIFTL(V,N) performs the N steps left-shift function
%	 on matrix V, by rows.

siz=size(v);
w=zeros(siz);
if n<siz(2)
    w(:,1:siz(2)-n)=v(:,n+1:siz(2));
end