程序设计与算法（二）算法基础》《第四周 二分》二分法求函数的零点 4142

/*
二分法求方程的根

*/
#include<iostream>
#include<cstdio>

using namespace std;
#define EPS 1e-6

double f(double x)
{
    return x*x*x*x*x - 15 * x*x*x*x + 85 * x *x*x- 225*x*x+274*x-121;
}
int main()
{
    double root, left = 1.5, right = 2.4,y;
    int times = 1;
    root = left + (right - left) / 2;
    y = f(root);
    while (fabs(y) > EPS)
    {
        if (y < 0)
        {
            right = root;
            
        }
        else
        {
            left = root;

        }
        root = left + (right - left) / 2;
        y = f(root);
        times++;
    }
    printf("%.8f\n", root);
    printf("%d\n", times);
    return 0;
}