#include<iostream.h>
#include<math.h>
float ff1(float x){
return (3*x+1)/x*x;
}
float ff2(float x){
return (x*x*x-1)/3;
}
float ff3(float x){
return 0;
}
float ff4(float x){
return 1/(x*x-3);
}
float ff5(float x){
return sqrt(3+1/x);
}
float ff6(float x){
return x-(x*x*x-3*x-1)/(3*(x*x-1));
}
float f(float x){
return x*x*x-x-1;
}
float f1(float x){
return 3*x*x-1;
}
float diedai(float (*ff)(float),float x1,float e,int N){
int k=0;
float x2;
while(k<=N){
x2=ff(x1);
x1=x2; cout<<x1<<endl;
cout<<x2<<endl;
if(fabs(x1-x2)<e){
cout<<"实际迭代次数：k="<<k+1<<endl;
return x2;
}
k++;
}
cout<<"超出迭代次数，迭代失败！"<<endl;
return -1;
}
float newton(float (*f)(float) ,float (*f1)(float),float x1,float e,int N,int M){
int k=0;
float x2;
while(k<=N){
if(f1(x1)==0){
cout<<"表达式倒数值为零！"<<endl;return -1;
}
else{
int i=0;float l=1;
while(i<=M){
x2=x1-l*f(x1)/f1(x1);
if(fabs(f(x2))>fabs(f(x1))){
cout<<x2<<" "<<l<<endl;
i++;
l=l*(float)0.5;
}
else break;
}
if(fabs(x2-x1)<e){
return x2;
}
else{
k++;x1=x2;
}
}
}
cout<<"超过迭代次数，迭代失败！"<<endl;
return -1;
}
void main(){
float x,e;
int N,M;
//cout<<"请输入数据"<<endl;
// cout<<"迭代初值：x=";cin>>x;cout<<endl;
// cout<<"误差限：e=";cin>>e;cout<<endl;
// cout<<"迭代最大次数：N=";cin>>N;cout<<endl;
// cout<<"下山最大次数:M=";cin>>M;cout<<endl;
cout<<"牛顿迭代后的结果为："<<endl;
// cout<<newton(f,f1,0.6,0.01,100,100)<<endl;
cout<<diedai(ff6,0.6,0.001,100);
}
