1 #ifndef STAN_MATH_PRIM_FUN_MAX_HPP
2 #define STAN_MATH_PRIM_FUN_MAX_HPP
3 
4 #include <stan/math/prim/meta.hpp>
5 #include <stan/math/prim/err.hpp>
6 #include <stan/math/prim/fun/Eigen.hpp>
7 #include <stan/math/prim/fun/constants.hpp>
8 #include <algorithm>
9 #include <vector>
10 
11 namespace stan {
12 namespace math {
13 
14 /**
15  * Returns the maximum coefficient in the specified
16  * matrix, vector, row vector or std vector.
17  *
18  * @tparam T type of the container
19  * @param m specified matrix, vector, row vector or std vector
20  * @return maximum coefficient value in the container, or -infinity if the
21  * container is size zero and the scalar type in container is floating point
22  * number
23  * @throws <code>std::invalid_argument</code> if the vector is size zero and the
24  * scalar type in the container is integer
25  */
26 template <typename T, require_container_t<T>* = nullptr>
max(const T & m)27 inline value_type_t<T> max(const T& m) {
28   if (std::is_integral<value_type_t<T>>::value) {
29     check_nonzero_size("max", "int vector", m);
30   } else if (m.size() == 0) {
31     return NEGATIVE_INFTY;
32   }
33   return apply_vector_unary<T>::reduce(
34       m, [](const auto& x) { return x.maxCoeff(); });
35 }
36 
37 }  // namespace math
38 }  // namespace stan
39 
40 #endif
41