数值计算方法：二分法求解方程的根（伪代码 python c/c++）

数值计算方法：二分法求解方程的根

伪代码

fun (input x)
	return x^2+x-6
newton (input a, input b, input e)
//a是区间下界，b是区间上界，e是精确度
	x <- (a + b) / 2
	if abs(b - 1) < e:
		return x
	else:
		if fun(a) * fun(b) < 0:
			return newton(a, x, e)
		else:
			return newton(x, b, e)
			

c/c++:

#include 
#include 
using namespace std;

double fun (double x);
double newton (double a, double b,double e);

int main()
{
	cout << newton(-5,0,0.5e-5);
	return 0;
}

double fun(double x)
{
	return pow(x,2)+x-6;
}

double newton (double a, double b, double e)
{
	double x;
	x = (a + b)/2;
	cout << x << endl;
	if ( abs(b-a) < e)
		return x;
	else
		if (fun(a)*fun(x) < 0)
			return newton(a,x,e);
		else
			return newton(x,b,e);
}

python：

def fun(x):
    return x ** 2 + x - 6
def newton(a,b,e):
    x = (a + b)/2.0
    if abs(b-a) < e:
        return x
    else:
        if fun(a) * fun(x) < 0:
            return newton(a, x, e)
        else:
            return newton(x, b, e)
print newton(-5, 0, 5e-5)