高考问答土耳其琉璃灯:C语言2分法
来源：百度文库 编辑：高考问答 时间：2024/05/05 09:42:23
求方程x3＋x2-3x-3=0在（0，5）内的解，要求误差小于10-9
#include <math.h>
double f(double x)
{
double y;
y=((x+1.0)*x-3.0)*x-3.0;
return(y);
}
double xpoint(double x1,double x2)
{
double y;
y=(x1*f(x2)-x2*f(x1))/(f(x2)-f(x1));
return(y);
}
double root(double x1,double x2)
{ double x,y,y1;
y1=f(x1);
do
{ x=xpoint(x1,x2);
y=f(x);
if(y*y1>0)
{ y1=y;
x1=x;
}
else
x2=x;
}while(fabs(y)>=0.000000001);
return(x);
}
main()
{ double x1,x2,f1,f2,x;
do
{ printf("input x1,x2:\n");
scanf("%f,%f",&x1,&x2); /* 输入0,5.0 */
f1=f(x1);
f2=f(x2);
}while(f1*f2>=0);
x=root(x1,x2);
printf("A root of equation is %15.9f",x);
}
给个悬赏分啊