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

using namespace std;

# include "golden_section.hpp"

int main ( );
double humps_fun ( double x );
double test_fun ( double x );
void timestamp ( );

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

int main ( )

//****************************************************************************80
//
//  Purpose:
//
//    golden_section_test() tests golden_section().
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    24 February 2026
//
//  Author:
//
//    John Burkardt
//
{
  double a;
  double b;
  int it;
  int n;
  double x_tol;

  timestamp ( );

  cout << "\n";
  cout << "golden_section_test():\n";
  cout << "  C++ version\n";
  cout << "  golden_section() seeks a minimizer\n";
  cout << "  of a function f(x) in the interval [a,b],\n";
  cout << "  assuming f(x) is unimodal over [a,b],\n";
//
//  humps(x) = 1 / ((x-0.3)^2 + 0.01) + 1 / ((x-0.9)^2 + 0.04) - 6.0
//
  a = 0.3;
  b = 0.9;
  n = 25;
  x_tol = 0.000001;

  cout << "\n";
  cout << "  f = humps_fun(x)\n";
  cout << "  f(" << a << ") = " << humps_fun ( a ) << "\n";
  cout << "  f(" << b << ") = " << humps_fun ( b ) << "\n";
  cout << "  iteration limit n = " << n << "\n";
  cout << "  x_tol = " << x_tol << "\n";
  golden_section ( humps_fun, n, x_tol, a, b, it );
  cout << "\n";
  cout << "  Number of iterations: " << it << "\n";
  cout << "  f(" << a << ") = " << humps_fun ( a ) << "\n";
  cout << "  f(" << b << ") = " << humps_fun ( b ) << "\n";
//
//  test_fun(x)=x^4+10*x*sin(x^2)
//
  a = -2.0;
  b = 1.0;
  n = 35;
  x_tol = 0.000001;

  cout << "\n";
  cout << "  f = test_fun(x)\n";
  cout << "  f(" << a << ") = " << test_fun ( a ) << "\n";
  cout << "  f(" << b << ") = " << test_fun ( b ) << "\n";
  cout << "  iteration limit n = " << n << "\n";
  cout << "  x_tol = " << x_tol << "\n";
  golden_section ( test_fun, n, x_tol, a, b, it );
  cout << "\n";
  cout << "  Number of iterations: " << it << "\n";
  cout << "  f(" << a << ") = " << test_fun ( a ) << "\n";
  cout << "  f(" << b << ") = " << test_fun ( b ) << "\n";
//
//  Terminate.
//
  cout << "\n";
  cout << "golden_section_test():\n";
  cout << "  Normal end of execution.\n";
  timestamp ( );

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

double humps_fun ( double x )

//****************************************************************************80
//
//  Purpose:
//
//    humps_fun() evaluates a function used for demonstrations.
//
//  Discussion:
//
//    The "interesting" portion of the function is visible over the range
//    0 <= x <= 2.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    29 June 2019
//
//  Author:
//
//    John Burkardt
//
//  Input:
//
//    double x: the evaluation point.
//
//  Output:
//
//    double humps_fun: the function value.
//
{
  double value;

  value = 1.0 / ( pow ( x - 0.3, 2 ) + 0.01 )
        + 1.0 / ( pow ( x - 0.9, 2 ) + 0.04 ) - 6.0;

  return value;
}
//****************************************************************************80

double test_fun ( double x )

//****************************************************************************80
//
//  Purpose:
//
//    test_fun() evaluates a function used for demonstrations.
//
//  Licensing:
//
//    This code is distributed under the MIT license.
//
//  Modified:
//
//    23 February 2026
//
//  Author:
//
//    John Burkardt
//
//  Input:
//
//    double x: the evaluation point.
//
//  Output:
//
//    double test_fun: the function value.
//
{
  double value;

  value = pow ( x, 4 ) + 10.0 * x * sin ( pow ( x, 2 ) );

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