# include <math.h>
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# include <time.h>

int main ( );
void timestamp ( );

/******************************************************************************/

int main ( )

/******************************************************************************/
/*
  Purpose:

    vortex_subplots() creates a color contour plot of orbital data.

  Licensing:

    This code is distributed under the MIT license.

  Modified:

    22 August 2026

  Author:

    John Burkardt
*/
{
  FILE *command_unit;

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

  command_unit = fopen ( "vortex_subplots_commands.txt", "wt" );

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

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

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

  fprintf ( command_unit, "#\n" );
  fprintf ( command_unit, "unset multiplot\n" );
  fprintf ( command_unit, "quit\n" );

  fclose ( command_unit );
  printf ( "  Created command file 'vortex_subplots_commands.txt'\n" );
/*
  Terminate.
*/
  printf ( "\n" );
  printf ( "vortex_subplots():\n" );
  printf ( "  Normal end of execution.\n" );
  timestamp ( );

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

void timestamp ( )

/******************************************************************************/
/*
  Purpose:
 
    timestamp() prints the current YMDHMS date as a time stamp.

  Example:

    17 June 2014 09:45:54 AM

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    01 May 2021

  Author:

    John Burkardt
*/
{
# define TIME_SIZE 40

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

  now = time ( NULL );
  tm = localtime ( &now );

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

  printf ( "%s\n", time_buffer );

  return;
# undef TIME_SIZE
}