check_symmetric.hpp

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#ifndef STAN__MATH__ERROR_HANDLING__MATRIX__CHECK_SYMMETRIC_HPP
#define STAN__MATH__ERROR_HANDLING__MATRIX__CHECK_SYMMETRIC_HPP

#include <sstream>

#include <stan/math/error_handling/dom_err.hpp>
#include <stan/math/error_handling/matrix/constraint_tolerance.hpp>
#include <stan/math/matrix/Eigen.hpp>
#include <stan/math/matrix/meta/index_type.hpp>
#include <stan/meta/traits.hpp>

namespace stan {

  namespace math {

    template <typename T_y, typename T_result>
    inline bool 
    check_symmetric(const char* function,
                    const Eigen::Matrix<T_y,Eigen::Dynamic,Eigen::Dynamic>& y,
                    const char* name,
                    T_result* result) {
      using Eigen::Dynamic;
      using Eigen::Matrix;
      typedef typename index_type<Matrix<T_y,Dynamic,Dynamic> >::type size_type;

      size_type k = y.rows();
      if (k == 1)
        return true;
      for (size_type m = 0; m < k; ++m) {
        for (size_type n = m + 1; n < k; ++n) {
          if (!(fabs(y(m,n) - y(n,m)) <= CONSTRAINT_TOLERANCE)) {
            std::ostringstream message;
            message << name << " is not symmetric. " 
                    << name << "[" << stan::error_index::value + m << "," 
                    << stan::error_index::value +n << "] is %1%, but "
                    << name << "[" << stan::error_index::value +n << "," 
                    << stan::error_index::value + m 
                    << "] element is " << y(n,m);
            std::string msg(message.str());
            return dom_err(function,y(m,n),name,
                           msg.c_str(),"",
                           result);
          }
        }
      }
      return true;
    }

  }
}
#endif