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

using namespace std;

int main ( );
void timestamp ( );

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    vortex_subplots() shows pressure and velocity as two subplots.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    22 August 2026
//
//  Author:
//
//    John Burkardt
//
{
  string command_filename;
  ofstream command_unit;

  timestamp ( );
  cout << "\n";
  cout << "vortex_subplots():\n";
  cout << "  C++ version\n";
  cout << "  Plot a pair of subplots together using gnuplot().\n";

  command_filename = "vortex_commands.txt";
  command_unit.open ( command_filename.c_str ( ) );

  command_unit << "# vortex_commands.txt\n";
  command_unit << "#\n";
  command_unit << "# Usage:\n";
  command_unit << "#  gnuplot < vortex_commands.txt\n";
  command_unit << "#\n";
  command_unit << "set term png\n";
  command_unit << "set output 'vortex_subplots.png'\n";
  command_unit << "set multiplot layout 1,2 title \"Vortex pressure and velocity\"\n";

  command_unit << "#\n";
  command_unit << "set xlabel '<--- X --->'\n";
  command_unit << "set ylabel '<--- Y --->'\n";
  command_unit << "set title 'Pressure'\n";
  command_unit << "set grid\n";
  command_unit << "set timestamp\n";
  command_unit << "unset key\n";
  command_unit << "unset surface\n";
  command_unit << "set contour base\n";
  command_unit << "set pm3d\n";
  command_unit << "set size ratio -1\n";
  command_unit << "unset tics\n";
  command_unit << "set view map scale 0.90\n";
  command_unit << "splot 'vortex_pressure_data.txt' with pm3d\n";

  command_unit << "#\n";
  command_unit << "set xlabel \"<--- X --->\"\n";
  command_unit << "set ylabel \"<--- Y --->\"\n";
  command_unit << "set title \"Velocity\"\n";
  command_unit << "unset key\n";
  command_unit << "set grid\n";
  command_unit << "set size ratio -1\n";
  command_unit << "plot \"vortex_velocity_data.txt\" using 1:2:5:6 with vectors \\\n";
  command_unit << "  head filled lt 2 linecolor rgb \"blue\"\n";

  command_unit << "#\n";
  command_unit << "unset multiplot\n";
  command_unit << "quit\n";

  command_unit.close ( );
  cout << "  Created command file 'vortex_commands.txt'\n";
//
//  Terminate.
//
  cout << "\n";
  cout << "vortex_subplots():\n";
  cout << "  Normal end of execution.\n";
  timestamp ( );

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