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

using namespace std;

# include "steinerberger.hpp"

int main ( );
void gnuplot_fx ( int n, double *x, double *y, string header );
double *r8vec_linspace_new ( int n, double a, double b );
void timestamp ( );

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    steinerberger_test() tests steinerberger().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    30 March 2025
//
//  Author:
//
//    John Burkardt
//
{
  double *fx;
  string header;
  char header_ch[30];
  int i;
  int j;
  int n;
  static int ntest[6] = { 1, 5, 10, 25, 50, 100 };
  int nx = 5001;
  double *x;

  timestamp ( );
  cout << "\n";
  cout << "steinerberger_test():\n";
  cout << "  C++ version\n";
  cout << "  Test steinerberger().\n";

  cout << "\n";
  cout << "  Plot f(n,x) for several values of n\n";
  cout << "\n";

  x = r8vec_linspace_new ( nx, 0.0, 1.0 );
  fx = new double[nx];
 
  for ( i = 0; i < 6; i++ )
  {
    n = ntest[i];
    for ( j = 0; j < nx; j++ )
    {
      fx[j] = steinerberger_function ( n, x[j] );
    }
//
//  This is a stupid workaround for the fact that sprintf can print
//  integers with a leading 0, into our filename string, but a purely
//  string-based solution is not obvious.
//
    sprintf ( header_ch, "steinerberger_%03d", n );
    header = header_ch;
    gnuplot_fx ( nx, x, fx, header );
  }

  delete [] fx;
  delete [] x;
//
//  Terminate.
//
  cout << "\n";
  cout << "steinerberger_test():\n";
  cout << "  Normal end of execution.\n";
  cout << "\n";
  timestamp ( );

  return 0;
}
//****************************************************************************80

void gnuplot_fx ( int n, double *x, double *y, string header )

//****************************************************************************80
//
//  Purpose:
//
//    gnuplot_fx() plots functional data x, f(x).
//
//  Discussion:
//
//    Actually, we simply create two files for processing by gnuplot().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    24 May 2024
//
//  Author:
//
//    John Burkardt
//
{
  string command_filename;
  ofstream command_unit;
  string data_filename;
  ofstream data_unit;
  int i;
  string png_filename;
//
//  Create a graphics data file.
//
  data_filename = header + "_data.txt";
  data_unit.open ( data_filename.c_str ( ) );
  for ( i = 0; i < n; i++ )
  {
    data_unit << x[i] << "  "
              << y[i] << "\n";
  }
  data_unit.close ( );
  cout << "  Created graphics data file '" << data_filename << "'\n";

  png_filename = header + ".png";
//
//  Create graphics command file.
//
  command_filename = header + "_commands.txt";
  command_unit.open ( command_filename.c_str ( ) );
  command_unit << "# " << command_filename << "\n";
  command_unit << "#\n";
  command_unit << "# Usage:\n";
  command_unit << "#  gnuplot < " << command_filename << "\n";
  command_unit << "#\n";
  command_unit << "set term png\n";
  command_unit << "set output '" << png_filename << "'\n";
  command_unit << "set xlabel '<--- X --->'\n";
  command_unit << "set ylabel '<-- Y(X) -->'\n";
  command_unit << "set title '" << header << "'\n";
  command_unit << "set grid\n";
  command_unit << "set style data lines\n";
  command_unit << 
    "plot '" << data_filename << "' using 1:2 lw 3 linecolor rgb 'blue'\n";
  command_unit.close ( );
  cout << "  Created command file '" << command_filename << "'\n";

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