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

# include "dislin_d.h"

int main ( int argc, char *argv[] );
void timestamp ( );

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

int main ( int argc, char *argv[] )

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

    QUICKPLOT_CONTOUR demonstrates the DISLIN quickplot command QPLCON.

  Licensing:

    This code is distributed under the MIT license. 

  Modified:
 
    28 February 2014

  Author:

    This C version by John Burkardt.

  Reference:

    Helmut Michels,
    The Data Plotting Software DISLIN - version 10.4,
    Shaker Media GmbH, January 2010,
    ISBN13: 978-3-86858-517-9.
*/
{
  int i;
  int j;
  int levels;
  int m = 100;
  int n = 100;
  double x;
  double y;
  double *zmat;

  timestamp ( );
  printf ( "\n" );
  printf ( "QUICKPLOT_SURFACE:\n" );
  printf ( "  C version:\n" );
  printf ( "  Demonstrate the DISLIN 'quickplot' command QPLCON\n" );
  printf ( "  to make a contour plot of data stored as a matrix.\n" );
/*
  Set up the data.
*/
  zmat = ( double * ) malloc ( m * n * sizeof ( double ) );

  for ( i = 0; i < m; i++ )
  {
    x = 1.6 * ( double ) ( i ) / ( double ) ( m - 1 );
    for ( j = 0; j < n; j++ )
    {
      y = 1.6 * ( double ) ( j ) / ( double ) ( n - 1 );
      zmat[i+j*m] = pow ( x * x - 1.0, 2 ) + pow ( y * y - 1.0, 2 );
    }
  }
/*
  Specify the format of the output file.
*/
  metafl ( "png" );
/*
  Specify that if a file already exists of the given name,
  the new data should overwrite the old.
*/
  filmod ( "delete" );
/*
  Specify the name of the output graphics file.
*/
  setfil ( "quickplot_contour.png" );
/*
  Choose the page size and orientation.
*/
  setpag ( "usal" );
/*
  For PNG output, reverse the default black background to white.
*/
  scrmod ( "reverse" );
/*
  Open DISLIN.
*/
  disini ( );
/*
  Label the axes and the plot.
*/
  name ( "<-- X -->", "X" );
  name ( "<-- Y -->", "Y" );
  titlin ( "Quick plot by QPLCON", 2 );
/*
  Draw the curve.
*/
  levels = 20;
  qplcon ( zmat, m, n, levels );
/*
  Close DISLIN.
*/
  disfin ( );
/*
  Free memory.
*/
  free ( zmat );
/*
  Terminate.
*/
  printf ( "\n" );
  printf ( "QUICKPLOT_CONTOUR:\n" );
  printf ( "  Normal end of execution.\n" );
  printf ( "\n" );
  timestamp ( );

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

void timestamp ( )

/******************************************************************************/
/*
  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:

    24 September 2003

  Author:

    John Burkardt

  Parameters:

    None
*/
{
# 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 );

  fprintf ( stdout, "%s\n", time_buffer );

  return;
# undef TIME_SIZE
}