text: 
  //=================================
  // include guard
  #ifndef __MATHGEOMETRY_INCLUDED__
  #define __MATHGEOMETRY_INCLUDED__
  
  #define REAL_IS_DOUBLE true
  #ifdef REAL_IS_DOUBLE
    typedef double real;
  #else
    typedef float real;
  #endif
  
  #include <cmath>
  
  #include "../include/array_template.hpp"
  #include "../include/EulerUnsteady2D_basic_package.h"
  
  real tri_area(real x1, real x2, real x3, real y1, real y2, real y3);
  
  //real sumArray2d(Array2D<real> A, int col);
  
  
  #endif