double search_interval(double x0,double& L, double& R, slice_function& g,double logy)
{
// assert(g(x0) > g(L) and g(x0) > g(R));
assert(g(x0) >= logy);
assert(L < R);
assert(L <= x0 and x0 <= R);
double L0 = L, R0 = R;
// std::cerr<<"** L0 = "<<L0<<" x0 = "<<x0<<" R0 = "<<R0<<std::endl;
for(int i=0;i<200;i++)
{
double x1 = L + uniform()*(R-L);
double gx1 = g(x1);
// std::cerr<<" L = "<<L <<" x = "<<g.current_value()<<" R = "<<R<<std::endl;
// std::cerr<<" logy = "<<logy<<"\n"; // logy_x0 = "<<logy_x0<<" logy_current = "<<g()<<std::endl;
if (gx1 >= logy) return x1;
if (x1 > x0)
R = x1;
else
L = x1;
}
std::cerr<<"Warning! Is size of the interval really ZERO?"<<std::endl;
double logy_x0 = g(x0);
std::cerr<<" L0 = "<<L0<<" x0 = "<<x0<<" R0 = "<<R0<<std::endl;
std::cerr<<" L = "<<L <<" x = "<<g.current_value()<<" R = "<<R<<std::endl;
std::cerr<<" logy = "<<logy<<" logy_x0 = "<<logy_x0<<" logy_current = "<<g()<<std::endl;
std::abort();
return x0;
}
double slice_sample(slice_function& g, double w, int m)
{
double x0 = g.current_value();
return slice_sample(x0,g,w,m);
}
