text: #ifndef STAN_MATH_REV_MAT_FUN_SCALE_MATRIX_EXP_MULTIPLY_HPP
  #define STAN_MATH_REV_MAT_FUN_SCALE_MATRIX_EXP_MULTIPLY_HPP
  
  #include <stan/math/rev/meta.hpp>
  #include <stan/math/prim/mat/fun/Eigen.hpp>
  #include <stan/math/prim/arr/err/check_nonzero_size.hpp>
  #include <stan/math/prim/mat/err/check_multiplicable.hpp>
  #include <stan/math/prim/mat/err/check_square.hpp>
  #include <stan/math/prim/mat/fun/matrix_exp.hpp>
  #include <stan/math/rev/mat/fun/multiply.hpp>
  #include <stan/math/rev/core.hpp>
  
  namespace stan {
  namespace math {
  
  /**
   * Return product of exp(At) and B, where A is a NxN matrix,
   * B is a NxCb matrix, and t is a double
   *
   * @tparam Ta scalar type matrix A
   * @tparam Tb scalar type matrix B
   * @tparam Cb Columns matrix B
   * @param[in] A Matrix
   * @param[in] B Matrix
   * @param[in] t double
   * @return exponential of At multiplies B
   */
  template <typename Ta, typename Tb, int Cb>
  inline Eigen::Matrix<typename stan::return_type<Ta, Tb>::type, -1, Cb>
  scale_matrix_exp_multiply(const double& t, const Eigen::Matrix<Ta, -1, -1>& A,
                            const Eigen::Matrix<Tb, -1, Cb>& B) {
    check_nonzero_size("scale_matrix_exp_multiply", "input matrix", A);
    check_nonzero_size("scale_matrix_exp_multiply", "input matrix", B);
    check_multiplicable("scale_matrix_exp_multiply", "A", A, "B", B);
    check_square("scale_matrix_exp_multiply", "input matrix", A);
    return multiply(matrix_exp(multiply(A, t)), B);
  }
  
  }  // namespace math
  }  // namespace stan
  
  #endif
  