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

# include "dislin_d.h"

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

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

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

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

    MAIN demonstrates the use of TeX for mathematical formulas.

  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.
*/
{
  char cstr[80];
  int nl;

  timestamp ( );
  printf ( "\n" );
  printf ( "EX14:\n" );
  printf ( "  C version\n" );
  printf ( "  Using TeX for mathematical formulas.\n" );
/*
  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 ( "ex14.png" );
/*
  Choose the page size and orientation.
*/
  setpag ( "usap" );
/*
  For PNG output, reverse the default black background to white.
*/
  scrmod ( "reverse" );
/*
  Open DISLIN.
*/
  disini ( );
/*
  Plot a border around the page.
*/
  pagera ( );
/*
  Use the COMPLEX font.
*/
  complx ( );
  height ( 40 );

  strcpy ( cstr, "TeX Instructions for Mathematical Formulas" );
  nl = nlmess ( cstr );
  messag ( cstr, ( 2100 - nl ) / 2, 100 );
  
  texmod ( "on" );
  messag ( "$\\frac{1}{x+y}$", 150, 400 );
  messag ( "$\\frac{a^2 - b^2}{a+b} = a - b$", 1200, 400 );
  
  messag ( "$r = \\red{\\sqrt{x^2 + y^2}}", 150, 700);
  messag ( "$\\cos \\phi = \\frac{x}{\\sqrt{x^2 + y^2}}$", 1200, 700 );

  messag ( "$\\Gamma(x) = \\int_0^\\infty e^{-t}t^{x-1}dt$", 150, 1000 );
  messag ( "$\\lim_{x \\to \\infty} (1 + \\frac{1}{x})^x = e$", 1200, 1000 );

  messag ( "$\\mu = \\sum_{i=1}^n x_i p_i$", 150, 1300 );
  messag ( "$\\mu = \\int_{-\\infty}^ \\infty x f(x) dx$", 1200, 1300 );

  messag ( "$\\overline{x} = \\frac{1}{n} \\sum_{i=1}^n x_i$", 150, 1600 );
  messag ( "$s^2 = \\frac{1}{n-1} \\sum_{i=1}^n (x_i - \\overline{x})^2$",
          1200, 1600 );

  messag ( "$\\sqrt[n]{\\frac{x^n - y^n}{1 + u^{2n}}}$", 150, 1900 );  
  messag ( "$\\sqrt[3]{-q + \\sqrt{q^2 + p^3}}$", 1200, 1900 );

  messag ( "$\\int \\frac{dx}{1+x^2} = \\arctan x + C$", 150, 2200 );
  messag ( "$\\int \\frac{dx}{\\sqrt{1+x^2}} = {\\rm arcsinh} x + C$",
          1200, 2200 );

  messag ( "$\\overline{P_1P_2} = \\sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}$",
           150, 2500 );
  messag ( "$x = \\frac{x_1 + \\lambda x_2}{1 + \\lambda}$", 1200, 2500 );
/*
  Close DISLIN.
*/
  disfin ( );
/*
  Terminate.
*/
  printf ( "\n" );
  printf ( "EX14:\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
}