# include <cstdlib>
# include <cstring>
# include <ctime>
# include <fstream>
# include <iomanip>
# include <iostream>

using namespace std;

# include "flame_exact.hpp"

int main ( );
double *r8vec_linspace_new ( int n, double a, double b );
void timestamp ( );

//****************************************************************************80

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    flame_exact_test() tests flame_exact().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    29 April 2024
//
//  Author:
//
//    John Burkardt
//
{
  int r = 4;
  int n = 101;

  string command_filename;
  ofstream command_unit;
  string data_filename;
  ofstream data_unit;
  string header = "flame_exact";
  int i;
  int j;
  double *t;
  double t0;
  double tstop;
  double *y;
  double y0;
  static double y0_vec[4] = { 0.005, 0.01, 0.02, 0.05 };

  timestamp ( );
  cout << "\n";
  cout << "flame_exact_test():\n";
  cout << "  C++ version\n";
  cout << "  flame_exact() evaluates the exact solution of the flame ODE.\n";
//
//  Get parameters.
//
  flame_parameters ( NULL, NULL, NULL, &t0, &y0, &tstop );
//
//  Extend time interval.
//
  tstop = 300.0;
  flame_parameters ( NULL, NULL, &tstop, NULL, NULL, NULL );

  cout << "\n";
  cout << "  parameters:\n";
  cout << "    t0    = " << t0 << "\n";
  cout << "    tstop = " << tstop << "\n";
//
//  Compute (t,y) pairs for n times, and r values of y0.
//
  t = r8vec_linspace_new ( n, t0, tstop );
  y = new double[n*r];

  for ( j = 0; j < r; j++ )
  {
    y0 = y0_vec[j];
    cout << "    y0 = " << y0 << "\n";
    flame_parameters ( NULL, &y0, NULL, NULL, NULL, NULL );
    flame_exact ( n, t, y + n*j );
  }
//
//  Create the data file.
//
  data_filename = header + "_data.txt";
  data_unit.open ( data_filename.c_str ( ) );

  for ( i = 0; i < n; i++ )
  {
    data_unit << t[i];
    for ( j = 0; j < r; j++ )
    {
      data_unit << "  " << y[i+j*n];
    }
    data_unit << "\n";
  }

  data_unit.close ( );
  cout << "\n";
  cout << "  Data stored in '" << data_filename << "'\n";
//
//  Create the command file.
//
  command_filename = header + "_commands.txt";
  command_unit.open ( command_filename.c_str ( ) );

  command_unit << "# " << command_filename << "\n";
  command_unit << "#\n";
  command_unit << "# Usage:\n";
  command_unit << "#  gnuplot < " << command_filename << "\n";
  command_unit << "#\n";
  command_unit << "set term png\n";
  command_unit << "set output '" << header << ".png'\n";
  command_unit << "set xlabel '<-- t -->'\n";
  command_unit << "set ylabel '<-- y(t) -->'\n";
  command_unit << "set title 'flame_exact:'\n";
  command_unit << "set grid\n";
  command_unit << "set style data lines\n";
  command_unit << "plot '" << data_filename << "' using 1:2 with lines lw 3,\\\n";
  command_unit << "     '" << data_filename << "' using 1:3 with lines lw 3,\\\n";
  command_unit << "     '" << data_filename << "' using 1:4 with lines lw 3,\\\n";
  command_unit << "     '" << data_filename << "' using 1:5 with lines lw 3\n";
  command_unit << "quit\n";

  command_unit.close ( );

  cout << "  Plot commands stored in '" << command_filename << "'\n";
//
//  Free memory.
//
  delete [] t;
  delete [] y;
//
//  Terminate.
//
  cout << "\n";
  cout << "flame_exact_test():\n";
  cout << "  Normal end of execution.\n";
  cout << "\n";
  timestamp ( );

  return 0;
}
//****************************************************************************80

double *r8vec_linspace_new ( int n, double a_first, double a_last )

//****************************************************************************80
//
//  Purpose:
//
//    r8vec_linspace_new() creates a vector of linearly spaced values.
//
//  Discussion:
//
//    An R8VEC is a vector of R8's.
//
//    4 points evenly spaced between 0 and 12 will yield 0, 4, 8, 12.
//
//    In other words, the interval is divided into N-1 even subintervals,
//    and the endpoints of intervals are used as the points.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    29 March 2011
//
//  Author:
//
//    John Burkardt
//
//  Parameters:
//
//    Input, int N, the number of entries in the vector.
//
//    Input, double A_FIRST, A_LAST, the first and last entries.
//
//    Output, double R8VEC_LINSPACE_NEW[N], a vector of linearly spaced data.
//
{
  double *a;
  int i;

  a = new double[n];

  if ( n == 1 )
  {
    a[0] = ( a_first + a_last ) / 2.0;
  }
  else
  {
    for ( i = 0; i < n; i++ )
    {
      a[i] = ( ( double ) ( n - 1 - i ) * a_first 
             + ( double ) (         i ) * a_last ) 
             / ( double ) ( n - 1     );
    }
  }
  return a;
}
//****************************************************************************80

void timestamp ( )

//****************************************************************************80
//
//  Purpose:
//
//    timestamp() prints the current YMDHMS date as a time stamp.
//
//  Example:
//
//    31 May 2001 09:45:54 AM
//
//  Licensing:
//
//    This code is distributed under the MIT license. 
//
//  Modified:
//
//    19 March 2018
//
//  Author:
//
//    John Burkardt
//
{
# define TIME_SIZE 40

  static char time_buffer[TIME_SIZE];
  const struct std::tm *tm_ptr;
  std::time_t now;

  now = std::time ( NULL );
  tm_ptr = std::localtime ( &now );

  std::strftime ( time_buffer, TIME_SIZE, "%d %B %Y %I:%M:%S %p", tm_ptr );

  std::cout << time_buffer << "\n";

  return;
# undef TIME_SIZE
}