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

using namespace std;

# include "doughnut_exact.hpp"

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

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    doughnut_exact_test() tests doughnut_exact().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    13 October 2025
//
//  Author:
//
//    John Burkardt
//
{
  string command_filename;
  ofstream command;
  string data_filename;
  ofstream data;
  int i;
  double m;
  double n;
  int nt;
  double *t;
  double t0;
  double tstop;
  double *y;
  double y0[3];

  timestamp ( );
  cout << "\n";
  cout << "doughnut_exact_test():\n";
  cout << "  C++ version\n";
  cout << "  Test doughnut_exact(), which evaluates exact solutions\n";
  cout << "  of the doughnut ODE.\n";

  doughnut_parameters ( NULL, NULL, NULL, NULL, NULL,
                        &m,   &n,   &t0,  y0,  &tstop );
  cout << "\n";
  cout << "  Parameter values:\n";
  cout << "    m      = " << m << "\n";
  cout << "    n      = " << n << "\n";
  cout << "    t0     = " << t0 << "\n";
  cout << "    y0     = " << y0[0] << ", " << y0[1] << ", " << y0[2] << "\n";
  cout << "    tstop  = " << tstop << "\n";

  nt = 1001;
  t = r8vec_linspace_new ( nt, t0, tstop );
  y = doughnut_exact ( nt, t );
//
//  Plot.
//
  data_filename = "doughnut_exact_data.txt";
  data.open ( data_filename.c_str ( ) );
  for ( i = 0; i < nt; i++ )
  {
    data << "  " << t[i]
         << "  " << y[0+i*3]
         << "  " << y[1+i*3]
         << "  " << y[2+i*3] << "\n";
  }
  data.close ( );
  cout << "  Created data file '" << data_filename << "'.\n";
//
//  Create the command file.
//
  command_filename = "doughnut_exact_commands.txt";
  command.open ( command_filename.c_str ( ) );
  command << "# " << command_filename << "\n";
  command << "#\n";
  command << "# Usage:\n";
  command << "#  gnuplot < " << command_filename << "\n";
  command << "#\n";
  command << "set term png\n";
  command << "set output 'doughnut_exact.png'\n";
  command << "set xlabel '<--- X(T) --->'\n";
  command << "set ylabel '<--- Y(T) --->'\n";
  command << "set zlabel '<--- Z(T) --->'\n";
  command << "set title '(X(T),Y(T),Z(T)) trajectory'\n";
  command << "set grid\n";
  command << "set style data lines\n";
  command << "splot '" << data_filename 
          << "' using 2:3:4 lw 2 linecolor rgb 'blue'\n";
  command << "quit\n";
  command.close ( );
  cout << "  Created command file '" << command_filename << "'\n";
//
//  Free memory.
//
  delete [] t;
  delete [] y;
//
//  Terminate.
//
  cout << "\n";
  cout << "doughnut_exact_test():\n";
  cout << "  Normal end of execution.\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
//
//  Input:
//
//    int N, the number of entries in the vector.
//
//    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
}