#ifndef STAN_MATH_PRIM_MAT_FUN_SUBTRACT_HPP
#define STAN_MATH_PRIM_MAT_FUN_SUBTRACT_HPP

#include <boost/math/tools/promotion.hpp>
#include <stan/math/prim/mat/fun/Eigen.hpp>
#include <stan/math/prim/mat/err/check_matching_dims.hpp>

namespace stan {
namespace math {

/**
 * Return the result of subtracting the second specified matrix
 * from the first specified matrix.  The return scalar type is the
 * promotion of the input types.
 *
 * @tparam T1 Scalar type of first matrix.
 * @tparam T2 Scalar type of second matrix.
 * @tparam R Row type of matrices.
 * @tparam C Column type of matrices.
 * @param m1 First matrix.
 * @param m2 Second matrix.
 * @return Difference between first matrix and second matrix.
 */
template <typename T1, typename T2, int R, int C>
inline Eigen::Matrix<typename boost::math::tools::promote_args<T1, T2>::type, R,
                     C>
subtract(const Eigen::Matrix<T1, R, C>& m1, const Eigen::Matrix<T2, R, C>& m2) {
  check_matching_dims("subtract", "m1", m1, "m2", m2);
  Eigen::Matrix<typename boost::math::tools::promote_args<T1, T2>::type, R, C>
      result(m1.rows(), m1.cols());
  for (int i = 0; i < result.size(); ++i)
    result(i) = m1(i) - m2(i);
  return result;
}

template <typename T1, typename T2, int R, int C>
inline Eigen::Matrix<typename boost::math::tools::promote_args<T1, T2>::type, R,
                     C>
subtract(const T1& c, const Eigen::Matrix<T2, R, C>& m) {
  Eigen::Matrix<typename boost::math::tools::promote_args<T1, T2>::type, R, C>
      result(m.rows(), m.cols());
  for (int i = 0; i < m.size(); ++i)
    result(i) = c - m(i);
  return result;
}

template <typename T1, typename T2, int R, int C>
inline Eigen::Matrix<typename boost::math::tools::promote_args<T1, T2>::type, R,
                     C>
subtract(const Eigen::Matrix<T1, R, C>& m, const T2& c) {
  Eigen::Matrix<typename boost::math::tools::promote_args<T1, T2>::type, R, C>
      result(m.rows(), m.cols());
  for (int i = 0; i < m.size(); ++i)
    result(i) = m(i) - c;
  return result;
}

}  // namespace math
}  // namespace stan
#endif
