double Distance(FV &distr_1, FV &distr_2) {
FV m(distr_1.size());
for (int i = 0; i < distr_1.size(); ++i) {
m[i] = (distr_1[i] + distr_2[i]) / 2.0;
}
return (KL(distr_1, m) + KL(distr_2, m)) / 2;
}
double KL(FV &p, FV &q) {
double kl = 0.0;
double denom1 = 0.0;
double denom2 = 0.0;
for (int i = 0; i < p.size(); ++i) {
// kl += p[i] * log(p[i] / q[i]);
kl += abs(p[i] - q[i]);
denom1 = p[i] * p[i];
denom2 = q[i] * q[i];
}
return kl;
}