typedef size_t size_type
#include <stan/memory/stack_alloc.hpp>
#include <stan/math/functions/sub.hpp>
#include <stan/math/functions/dot_self.hpp>
implement min of two scalars logically
#include <stan/math/functions/sub.hpp>
#include <stan/math/functions/dot_self.hpp>
implement min of two scalars logically again
#include <cstddef>
#include <cmath>
another #include <cstddef>
yet another #include <cstddef>
final #include <cstddef>
really final #include <cstddef>