#ifndef STAN_MATH_PRIM_MAT_FUN_DOT_PRODUCT_HPP
#define STAN_MATH_PRIM_MAT_FUN_DOT_PRODUCT_HPP

#include <stan/math/prim/mat/fun/Eigen.hpp>
#include <stan/math/prim/mat/err/check_vector.hpp>
#include <stan/math/prim/arr/err/check_matching_sizes.hpp>
#include <vector>

namespace stan {
namespace math {
/**
 * Returns the dot product of the specified vectors.
 *
 * @param v1 First vector.
 * @param v2 Second vector.
 * @return Dot product of the vectors.
 * @throw std::domain_error If the vectors are not the same
 * size or if they are both not vector dimensioned.
 */
template <int R1, int C1, int R2, int C2>
inline double dot_product(const Eigen::Matrix<double, R1, C1> &v1,
                          const Eigen::Matrix<double, R2, C2> &v2) {
  check_vector("dot_product", "v1", v1);
  check_vector("dot_product", "v2", v2);
  check_matching_sizes("dot_product", "v1", v1, "v2", v2);
  return v1.dot(v2);
}
/**
 * Returns the dot product of the specified arrays of doubles.
 * @param v1 First array.
 * @param v2 Second array.
 * @param length Length of both arrays.
 */
inline double dot_product(const double *v1, const double *v2, size_t length) {
  double result = 0;
  for (size_t i = 0; i < length; i++) {
    result += v1[i] * v2[i];
  }
  return result;
}
/**
 * Returns the dot product of the specified arrays of doubles.
 * @param v1 First array.
 * @param v2 Second array.
 * @throw std::domain_error if the vectors are not the same size.
 */
inline double dot_product(const std::vector<double> &v1,
                          const std::vector<double> &v2) {
  check_matching_sizes("dot_product", "v1", v1, "v2", v2);
  return dot_product(&v1[0], &v2[0], v1.size());
}
}  // namespace math
}  // namespace stan
#endif
