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

using namespace std;

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

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    correlation_heat_map() creates a heat map of a correlation matrix.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    24 April 2025
//
//  Author:
//
//    John Burkardt
//
{
  double cmax;
  double cmin;
  string command_filename;
  ofstream command_unit;
  double xmax;
  double xmin;
  double ymax;
  double ymin;

  timestamp ( );
  cout << "\n";
  cout << "correlation_heat_map():\n";
  cout << "  C++ version\n";
  cout << "  Heat map of a correlation matrix using gnuplot().\n";

  cmin = 0.28;
  cmax = 1.00;

  command_filename = "correlation_heat_map_commands.txt";
  command_unit.open ( command_filename.c_str ( ) );
  command_unit << "# correlation_heat_map_commands.txt\n";
  command_unit << "#\n";
  command_unit << "# Usage:\n";
  command_unit << "#  gnuplot < correlation_heat_map_commands.txt\n";
  command_unit << "#\n";
  command_unit << "set term png\n";
  command_unit << "set output 'correlation_heat_map.png'\n";
  command_unit << "set xlabel '<--- X --->'\n";
  command_unit << "set ylabel '<--- Y --->'\n";
  command_unit << "set title 'Heat map of correlation data'\n";
  command_unit << "unset key\n";
  command_unit << "set tic scale 0\n";
  command_unit << "set palette rgbformula 21, 22, 23\n";
  command_unit << "set cbrange [" << cmin << ":" << cmax << "]\n";
  command_unit << "unset cbtics\n";
//
//  These relate to the 1x8 range of i and j.
//
  xmin = -0.5;
  xmax = 7.5;
  ymin = -0.5;
  ymax = 7.5;
  command_unit << "set xrange [" << xmin << ":" << xmax << "]\n";
  command_unit << "set yrange [" << ymax << ":" << ymin << "]\n";
  command_unit << "set size square\n";
  command_unit << "set view map\n";
  command_unit << "splot 'correlation_data.txt' matrix with image\n";
  command_unit << "quit\n";
  command_unit.close ( );
  cout << "  Created command file 'correlation_heat_map_commands.txt'\n";
//
//  Terminate.
//
  cout << "\n";
  cout << "correlation_heat_map():\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
}