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

using namespace std;

# include "biharmonic_exact.hpp"

int main ( );
void timestamp ( );

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    biharmonic_exact_test() tests biharmonic_exact().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    02 August 2024
//
//  Author:
//
//    John Burkardt
//
{
  double a;
  double b;
  double c;
  double d;
  double e;
  double f;
  double g;
  int i;
  int n = 5;
  double r;
  double x;
  double y;

  timestamp ( );
  cout << "\n";
  cout << "biharmonic_exact_test():\n";
  cout << "  C++ version\n";
  cout << "  Test biharmonic_exact().\n";

  a = 1.0;
  b = 2.0;
  c = 3.0;
  d = 4.0;
  e = 5.0;
  f = 6.0;
  g = 7.0;
//
//  Exact function 1.
//
  cout << "\n";
  cout << "  Exact solution 1 residual at random points:\n";

  for ( i = 0; i < n; i++ )
  {
    x = drand48 ( );
    y = drand48 ( );
    r = biharmonic_exact_r1 ( x, y, a, b, c, d, e, f, g );
    cout << "  " << setw(2) << i
         << "  " << setw(10) << x
         << "  " << setw(10) << y
         << "  " << setw(14) << r << "\n";
  }
//
//  Exact function 2.
//
  cout << "\n";
  cout << "  Exact solution 2 residual at random points:\n";

  for ( i = 0; i < n; i++ )
  {
    x = drand48 ( );
    y = drand48 ( );
    r = biharmonic_exact_r2 ( x, y, a, b, c, d, e, f, g );
    cout << "  " << setw(2) << i
         << "  " << setw(10) << x
         << "  " << setw(10) << y
         << "  " << setw(14) << r << "\n";
  }
//
//  Exact function 3.
//
  cout << "\n";
  cout << "  Exact solution 3 residual at random points:\n";

  for ( i = 0; i < n; i++ )
  {
    x = drand48 ( );
    y = drand48 ( );
    r = biharmonic_exact_r3 ( x, y, a, b, c, d, e, f );
    cout << "  " << setw(2) << i
         << "  " << setw(10) << x
         << "  " << setw(10) << y
         << "  " << setw(14) << r << "\n";
  }
//
//  Terminate.
//
  cout << "\n";
  cout << "biharmonic_exact_test():\n";
  cout << "  Normal end of execution.\n";
  cout << "\n";
  timestamp ( );

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