function res = psikdelta(k,t,sp,vep,k0)

l = length(sp);
s = 0;
n = 0;

for m = 1:l
    s = s +vep(k0,m)*vep(k,m)*exp(-i*t*sp(m));
end

for mm = 1:l
    n = n+ abs(vep(k0,mm))^2;
end


res = s/sqrt(n);
end


