check_simplex.hpp

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#ifndef __STAN__MATH__ERROR_HANDLING__MATRIX__CHECK_SIMPLEX_HPP__
#define __STAN__MATH__ERROR_HANDLING__MATRIX__CHECK_SIMPLEX_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_prob, typename T_result>
    bool check_simplex(const char* function,
                       const Eigen::Matrix<T_prob,Eigen::Dynamic,1>& theta,
                       const char* name,
                       T_result* result) {
      using Eigen::Dynamic;
      using Eigen::Matrix;
      typedef typename index_type<Matrix<T_prob,Dynamic,1> >::type size_t;

      if (theta.size() == 0) {
        std::stringstream msg;
        msg << " is not a valid simplex. " 
            << "length(" << name << ") = %1%";
        std::string tmp(msg.str());
        return dom_err(function,0,name,
                       tmp.c_str(),"",
                       result);
      }
      if (!(fabs(1.0 - theta.sum()) <= CONSTRAINT_TOLERANCE)) {
        std::stringstream msg;
        T_prob sum = theta.sum();
        msg << " is not a valid simplex.";
        msg.precision(10);
        msg << " sum(" << name << ") = " << sum
            << ", but should be %1%";
        std::string tmp(msg.str());
        return dom_err(function,1.0,name,
                       tmp.c_str(),"",
                       result);
      }
      for (size_t n = 0; n < theta.size(); n++) {
        if (!(theta[n] >= 0)) {
          std::ostringstream stream;
          stream << " is not a valid simplex. "
                 << name << "[" << n + stan::error_index::value << "]"
                 << " = %1%, but should be greater than or equal to 0";
          std::string tmp(stream.str());
          return dom_err(function,theta[n],name,
                         tmp.c_str(),"",
                         result);
        }
      }
      return true;
    }                         

  }
}
#endif