refstring=refstr(Nf)

function refstring=refstr(Nf)

inp=1:Nf;
y=inp;
ns=log2(2*length(inp))-1;
s(ns,:)=[ones(1,length(inp)) inp];

while(ns>1)
a(1,:)=y(1:2:end);
y=a;
onesm=ones(1,length(a));
length(onesm);
rp=[onesm a(1,:)];
clear a onesm;
s(ns-1,:)=repmat(rp,1,2*length(inp)/length(rp));
ns=ns-1;
end
refstring=s;