Replace boost::isfinite, etc. with std:: versions #1010

 if (!(boost::math::isfinite)(value_of_rec(y)))

#ifndef STAN_MATH_PRIM_MAT_FUN_ADD_HPP
#define STAN_MATH_PRIM_MAT_FUN_ADD_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 sum of the specified matrices.  The two matrices
 * must have the same dimensions.
 * @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 Sum of the matrices.
 * @throw std::invalid_argument if m1 and m2 do not have the same
 * dimensions.
 */
template <typename T1, typename T2, int R, int C>
inline auto
add(const Eigen::Matrix<T1, R, C>& m1, const Eigen::Matrix<T2, R, C>& m2) {
  check_matching_dims("add", "m1", m1, "m2", m2);
  return (m1 + m2).eval();
}

/**
 * Return the sum of the specified matrix and specified scalar.
 *
 * @tparam T1 Scalar type of matrix.
 * @tparam T2 Type of scalar.
 * @param m Matrix.
 * @param c Scalar.
 * @return The matrix plus the scalar.
 */
template <typename T1, typename T2, int R, int C>
inline auto
add(const Eigen::Matrix<T1, R, C>& m, const T2& c) {
  return (m.array() + c).matrix().eval();
}

/**
 * Return the sum of the specified scalar and specified matrix.
 *
 * @tparam T1 Type of scalar.
 * @tparam T2 Scalar type of matrix.
 * @param c Scalar.
 * @param m Matrix.
 * @return The scalar plus the matrix.
 */
template <typename T1, typename T2, int R, int C>
inline auto
add(const T1& c, const Eigen::Matrix<T2, R, C>& m) {
  return add(m, c);
}

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