1 #ifndef STAN_MATH_PRIM_FUN_INVERSE_HPP
2 #define STAN_MATH_PRIM_FUN_INVERSE_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 
8 namespace stan {
9 namespace math {
10 
11 /**
12  * Returns the inverse of the specified matrix.
13  *
14  * @tparam T type of elements in the matrix
15  * @tparam R number of rows, can be Eigen::Dynamic
16  * @tparam C number of columns, can be Eigen::Dynamic
17  *
18  * @param m specified matrix
19  * @return Inverse of the matrix (an empty matrix if the specified matrix has
20  * size zero).
21  * @throw std::invalid_argument if the matrix is not square.
22  */
23 template <typename EigMat,
24           require_eigen_vt<std::is_arithmetic, EigMat>* = nullptr>
25 inline Eigen::Matrix<value_type_t<EigMat>, EigMat::RowsAtCompileTime,
26                      EigMat::ColsAtCompileTime>
inverse(const EigMat & m)27 inverse(const EigMat& m) {
28   check_square("inverse", "m", m);
29   if (m.size() == 0) {
30     return {};
31   }
32   return m.inverse();
33 }
34 
35 }  // namespace math
36 }  // namespace stan
37 
38 #endif
39