//******************************************************************
//   HEADER FILE for program hpvloop.cpp                           *
//   FILENAME:      hpvloop.h                                      *
//   PROGRAMMER:    Dr.Iz (Urieli)                                 *
//   DATE:          01/17/04    (updated 10/5/07)                  *
//******************************************************************
using namespace std;
class HPvehicle { // human powered vehicle
  private:
    float cda,     // [sq.m] - (coefficient of drag * frontal area)
          cr,      // [-] - coefficient of rolling resistance
          mass;    // [kg] - mass of hpv + rider
  public:
    float g,        // [m/s/s] - acceleration due to gravity
          density,  // [kg/cu.m] - air density
          wind_mph, // [mph] - wind velocity (positive for headwind)
          slope;    // [-] - height/distance - (positive for uphill)
    //===============================================================
    HPvehicle( // Constructor initialization
       float mass0 = 92.0,  // [kg] - 15 kg bike, 77 kg rider typical
       float cda0 = 0.4, // [sq.m] - upright city bicycle
       float cr0 = 0.005) // [-] - high pressure tires on flat road
    { 
       mass = mass0;
       cda = cda0;
       cr = cr0;
       cout << "hpv initialised as follows:\n"
            << " mass (hpv + rider): " << mass << "[kg]\n"
            << " cda (coeff.drag*area): " << cda << "[sq.m]\n"
            << " cr (coeff.rolling resist): " << cr << endl;
       g = 9.807; // [m/s/s] - standard acceleration due to gravity
       density = 1.18; // [kg/cu.m] - sea level standard air density
       wind_mph = slope = 0;
       cout << "local conditions initialised as follws:\n"
            << " gravity acceleration: " << g << "[m/s/s]\n"
            << " air density: " << density << "[kg/cu.m]\n"
            << " wind velocity: " << wind_mph << "[mph]\n"
            << " slope: " << slope << endl;
       cout << "-----------------------------------------------------\n";
    }
    //===============================================================
    float find_power(float vel_mph)
    {  // applied power [watts] as function of velocity [mph]
       // pre: argument vel_mph and all private and public variables
       //      have values
       // post: power (watts) has been evaluated and returned
       const float CONVERT = (4.0/9.0); // mph to meters/sec
       float vel, // velocity converted to m/s  
             wvel, // wind velocity converted to m/s 
             drag, // resistance due to wind drag [N]
             resist, // resistance due to rolling and slope [N]
             power; // applied power to wheels [watts]

       vel = CONVERT * vel_mph;
       wvel = CONVERT * wind_mph;
       drag = cda*density*(vel + wvel)*(vel + wvel)/2.0;
       resist = mass*g*(cr + slope);
       power = vel*(drag + resist);

       return power;
    }
    //===============================================================
    float find_root(float lo_vel, float hi_vel, float epsilon);
       // find the root of "find_power" using the bisection method
       // pre:  float bounds [lo_vel, hi_vel] have values
       //       epsilon (allowable error in root) has a value
       // post: either the root "mid_vel" has been determined within a
       //       tolerance epsilon and has been returned
       //       or a warning message has been displayed
    //===============================================================
};
//================================================================
// general function prototypes:
float get_wind(); // get the wind velocity from the keyboard
float get_slope(); // get the slope from the keyboard
//================================================================