//*********************************************************************
//   PURPOSE:       header file for balplot.cpp                       *
//   FILENAME:      balplot.h                                         *
//   PROGRAMMER:    Dr.Iz (Urieli)                                    *
//   DATE:          03/27/04                                          *
//*********************************************************************
using namespace std;
class Balloon { // hot air balloon
  private:
    float volume,     // [cu.m] - balloon volume
          mass;    // [kg] - balloon empty mass
  public:
    float lapse,  // [deg C/m] - temperature lapse rate   
          temp0,  // [deg C] - temperature at sea level  
          pres0,  // [Pa] - standard pressure at sea level  
          rgas,   // [J/kg K] - gas constant of air  
          g; // [m/s/s] - acceleration due to gravity  
    //===============================================================
    Balloon( // Constructor initialization
       float volume0 = 1000.0,  // [cu.m]
       float mass0 = 100.0) // [kg] - balloon empty mass
    { 
       volume = volume0;
       mass = mass0;
       lapse = -6.5e-3; // [deg C/m] - temperature lapse rate   
       temp0 = 15.0;    // [deg C] - temperature at sea level  
       pres0 = 101325.0; // [Pa] - standard pressure at sea level  
       rgas = 287.0;    // [J/kg K] - gas constant of air  
       g = 9.807; // [m/s/s] - standard acceleration due to gravity
       cout << "balloon initialised as follows:\n"
            << " balloon volume: " << volume << "[cu.m]\n"
            << " balloon empty mass: " << mass << "[kg]\n";
       cout << "standard atmospheric conditions:\n"
            << " temperature lapse rate: " << lapse << "[deg C/m]\n"
            << " temperature at sea level: " << temp0 << "[deg C]\n"
            << " standard pressure at sea level: " << pres0 << "[Pa]\n";
    }
    //===============================================================
    float find_payload(float altitude); // prototype
      // determine balloon payload [kg] as function of altitude [m]
      // pre: all private and public variables & altitude have values
      // post: value of payload is returned
      // if altitude negative or >11,000m payload is not evaluated
      // and payload mass of zero is returned
      // Dr.Iz (Urieli) 03/25/04
    //===============================================================
    float find_altitude(float req_payload,
                    float lo_alt, float hi_alt, float epsilon);
       // find the altitude (root of {find_payload - req_payload}) within
       // [lo_alt,hi_alt] within error bound "epsilon" using bisection
       // pre:  req_payload (required payload) has a value
       //       float bounds [lo_alt, hi_alt] have values
       //       epsilon (allowable error in root) has a value
       // post: either the root "mid_alt" has been determined within a
       //       tolerance epsilon and has been returned
       //       or a warning message has been displayed
    //===============================================================
    float dif_payload(float altitude, float req_payload){
         // pre: arguments altitude and req_payload have values
         // post: difference of actual and required payload is returned
          return (find_payload(altitude) - req_payload);
    }
    //===============================================================
    void funarrays(float lo_alt, float hi_alt, 
                   float alt[], float pay[], int n);
    //   creates two coordinate arrays of n components: altitude (alt)
    //   and payload (pay), for (n-1) equally divided altitude intervals 
    //   between lo_alt and hi_alt.
    //===========================================================
    void savearrays(float alt[], float pay[], int n);
    //   save the two arrays on a data file in two columns 
    //   separated by tabs. The filename is entered from the keyboard.
    //===========================================================
};
//================================================================
void get_balloon(float& volume, float& mass);
    // get the basic balloon data from a balloon-file
    // pre: text data file exists (else program aborts)
    // post: reference arguments volume and mass have values
//===============================================================
int const SIZE = 100; // maximum size of the arrays 
//================================================================