mdivide_right_tri.hpp

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#ifndef STAN__MATH__MATRIX__MDIVIDE_RIGHT_TRI_HPP
#define STAN__MATH__MATRIX__MDIVIDE_RIGHT_TRI_HPP

#include <stdexcept>
#include <boost/math/tools/promotion.hpp>
#include <stan/math/matrix/Eigen.hpp>
#include <stan/math/matrix/mdivide_left_tri.hpp>
#include <stan/math/matrix/transpose.hpp>
#include <stan/math/error_handling/matrix/check_multiplicable.hpp>
#include <stan/math/error_handling/matrix/check_square.hpp>

namespace stan {
  namespace math {

    template <int TriView, typename T1, typename T2, 
              int R1, int C1, int R2, int C2>
    inline 
    Eigen::Matrix<typename boost::math::tools::promote_args<T1,T2>::type,R1,C2>
    mdivide_right_tri(const Eigen::Matrix<T1,R1,C1> &b,
                      const Eigen::Matrix<T2,R2,C2> &A) {
      stan::math::check_square("mdivide_right_tri(%1%)",A,"A",(double*)0);
      stan::math::check_multiplicable("mdivide_right_tri(%1%)",b,"b",
                                      A,"A",(double*)0);
      // FIXME: This is nice and general but requires some extra memory and copying.
      if (TriView == Eigen::Lower) {
        return transpose(mdivide_left_tri<Eigen::Upper>(transpose(A),transpose(b)));
      }
      else if (TriView == Eigen::Upper) {
        return transpose(mdivide_left_tri<Eigen::Lower>(transpose(A),transpose(b)));
      }
      else {
        throw std::domain_error("triangular view must be Eigen::Lower or Eigen::Upper");
      }
    }

  }
}
#endif