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  1. #include <iostream>
  2. #include <fstream>
  3. #include <cmath>
  4. #include <cstdlib>
  5.  
  6. using namespace std;
  7.  
  8. double f(double x)
  9. {
  10.     return 0.25 * x * x - 2.0;
  11. }
  12.  
  13. int main()
  14. {
  15.     double a = 2.0;
  16.     double b = 4.0;
  17.     double eps = 1e-6;
  18.     double c;
  19.  
  20.     if (f(a) * f(b) >= 0)
  21.     {
  22.         cout << "Brak zmiany znaku w przedziale!" << endl;
  23.         return 1;
  24.     }
  25.  
  26.     // Metoda bisekcji
  27.     while ((b - a) > eps)
  28.     {
  29.         c = (a + b) / 2.0;
  30.  
  31.         if (f(a) * f(c) < 0)
  32.             b = c;
  33.         else
  34.             a = c;
  35.     }
  36.  
  37.     double root = (a + b) / 2.0;
  38.     cout << "Miejsce zerowe: x = " << root << endl;
  39.  
  40.     // Zapis danych do wykresu
  41.     ofstream data("dane.txt");
  42.     for (double x = 1.5; x <= 4.5; x += 0.01)
  43.         data << x << " " << f(x) << endl;
  44.     data.close();
  45.  
  46.     // Skrypt gnuplot
  47.     ofstream gp("wykres.gp");
  48.     gp << "set terminal jpeg size 800,600\n";
  49.     gp << "set output 'wykres.jpg'\n";
  50.     gp << "set grid\n";
  51.     gp << "set xlabel 'x'\n";
  52.     gp << "set ylabel 'f(x)'\n";
  53.     gp << "set title 'Wykres f(x) = (1/4)x^2 - 2'\n";
  54.     gp << "plot 'dane.txt' with lines title 'f(x)', \\\n";
  55.     gp << root << " title 'miejsce zerowe'\n";
  56.     gp.close();
  57.  
  58.     system("gnuplot wykres.gp");
  59.  
  60.     return 0;
  61. }
  62.  
Success #stdin #stdout #stderr 0.01s 5288KB
comments (?)
stdin
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Standard input is empty
stdout
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Miejsce zerowe: x = 2.82843
stderr
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sh: 1: gnuplot: not found
https://ideone.com/7nVkqj
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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