C++ Bc. 29 cpp

#include <iostream>
#include <cmath>
#include <string>

struct Chyba
{
  template <typename T> Chyba(T t) : text(t) {}

  std::string text;
};


typedef double (*Funkce)(double);
double tetivy(Funkce f, double a, double b, double tol=1e-12) throw (Chyba);


double test(double x)
{
  return std::sin(4*x*x - x - 0.3);
}

int main()
{
  try 
    {
      double d =tetivy(test, -1, 1);
      std::cout << "Aproximace korene x = " << d 
                << "    f(x) = " << test(d) << "\n";
    }
  catch(Chyba chyba)
    {
      std::cout << chyba.text << "\n";
    }
}


double tetivy(Funkce f, double a, double b, double tol) throw (Chyba)
{
  double fa = f(a);
  double fb = f(b);
  double x, fx;

  if (fa*fb > 0) throw Chyba("Neni splnena podminka f(a)*f(b) < 0\n");
  if (std::abs(a - b) < tol) return a;

  do 
    {    
      x  = (b*fa - a*fb)/(fa - fb);
      fx = f(x);
      
      if (fa*fx > 0)
        {
          a  = x;
          fa = fx;
        }
      else
        {
          b  = x;
          fb = fx;
        } 
    } 
  while (std::abs(fx) > tol && std::abs(a - b) > tol);
   
  return x;
}

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