# include <cstdlib>
# include <ctime>
# include <iomanip>
# include <iostream>

using namespace std;

# include "sine_gordon_exact.hpp"

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

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    sine_gordon_exact_test() tests sine_gordon_exact().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    02 May 2024
//
//  Author:
//
//    John Burkardt
//
{
  double a;
  int i;
  int j;
  int nx = 6;
  int ny = 6;
  double r;
  double u;
  double uxy;
  double *x;
  double *y;

  timestamp ( );
  cout << "\n";
  cout << "sine_gordon_exact_test():\n";
  cout << "  C++ version\n";
  cout << "  Test sine_gordon_exact().\n";

  a = 1.5;

  cout << "\n";
  cout << "  Parameters:\n";
  cout << "    a     = " << a << "\n";

  cout << "\n";
  cout << "  Evaluate solution and residual at selected points (X,Y)\n";

  x = r8vec_linspace_new ( nx, 0.0, 1.0 );
  y = r8vec_linspace_new ( ny, 0.0, 1.0 );

  cout << "\n";
  cout << "      X       Y       U(X,Y)      Resid(X,Y)\n";
  cout << "\n";
  for ( j = 0; j < ny; j++ )
  {
    for ( i = 0; i < nx; i++ )
    {
      sine_gordon_exact ( a, x[i], y[j], &u, &uxy );
      r = sine_gordon_residual ( u, uxy );
      cout << setw(14) << x[i]
           << setw(14) << y[j]
           << setw(14) << u
           << setw(14) << r << "\n";
    }
    cout << "\n";
  }

  delete [] x;
  delete [] y;
//
//  Terminate.
//
  cout << "\n";
  cout << "sine_gordon_exact_test():\n";
  cout << "  Normal end of execution.\n";
  cout << "\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
//
//  Parameters:
//
//    Input, int N, the number of entries in the vector.
//
//    Input, 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
}