复制内容到剪贴板
代码:
#include<iostream.h>
#include<math.h>
#define N 100
#define EPS 1e-6
#define ETA 1e-8
void main()
{
float f(float);
float f1(float);
float x0,y0;
float Newton(float (*)(float),float (*)(float),float);
cout<<"Please input x0\n";
cin>>x0;
cout<<"x(0)="<<x0<<endl;
y0=Newton(f,f1,x0);
cout<<"\nThe root of the equation is x="<<(float)y0<<endl;
}
float Newton(float (*f)(float),float (*f1)(float),float x0)
{
float x1,d;
int k=0;
do{
x1=x0-f(x0)/f1(x0);
if((k++>N)||(fabs(f1(x1))<EPS))
{
cout<<"\nNewton method faild!";
return 0;
}
d=(fabs(x1)<1?x1-x0:(x1-x0)/x1);
x0=x1;
cout<<"x("<<k<<")="<<x0<<endl;
}
while(fabs(d)>EPS&&fabs(f(x1))>ETA);
return 1;
}
float f(float x)
{
// return log(x)+x-2;
return x*x*x+x*x-3*x-3;
}
float f1(float x)
{
// return 1/x+1;
return 3.0*x*x+2*x-3;
}
