ex04-05.cpp

数据结构常用算法合集

//EX04-06.cpp
//find the root of y=exp(-x)-x using the method of "BISECTION" 
#include <iostream.h>	//cout,cin
#include <math.h>		// exp()
#include <iomanip.h>	// setw()
#include <conio.h>	// getch()
float root(float x);
void main()
{ float xl,xu,xr;	//xl:lower xu:upper xr:root
  int count = 0;
  cout << "Enter xl,xu:";
  cin >> xl >> xu;
  cout << "=============================\n";
  cout << "No     xl       xu        xr\n";
  cout << "=============================\n";
  if (root(xl)*root(xu)<0)
  { do
    { xr = (xl + xu)/2;
      count++;
      if (root(xl)*root(xr)<0)
      xu = xr;
      if (root(xl)*root(xr)>0)
      xl = xr;
      cout << setw(2) << count << " "
           << setw(8) << setiosflags(ios::fixed) << setprecision(6)<< xl << " "
           << setw(8) << setiosflags(ios::fixed) << setprecision(6)<<xu << " "
           << setw(8) << setiosflags(ios::fixed) << setprecision(6)<<xr << endl;
    } while (count<=20);
    cout << "=============================\n";
  }	//for < 0
  getch();	//pause
}
//--------- function of exp(-x)-x
float root(float x)
{ return exp(-x)-x; }