Question

C语言中二分法的编程

谁能帮我用二分法求方程x3-3x2+2x-6=0在（-20，20）之间的根，要求绝对误差不超过0.001

Answer 1

#include <stdio.h>
#include <math.h>
void main()
{int x1,x2,x,f1,f2;
f1=x1*x1*x1-3*x1*x1-2*x1-6;
f2=x2*x2*x2-3*x2*x2-2*x2-6;
do
{scanf("%d%d",x1,x2);
}while(f1*f2>0);
do
{x=(x1+x2)/2;
f=x*x*x-3*x*x-2*x-6;
if(f*f1<0)
{x2=x;
f2=f;}
if(f*f2<0)
{x1=x;
f1=f;}
}while(fabs(x1-x2)>0.001);
printf("%d",x);}

Answer 2

#include
<stdio.h>
#include
<math.h>
void
main()
{int
x1,x2,x,f1,f2;f1=x1*x1*x1-3*x1*x1-2*x1-6;f2=x2*x2*x2-3*x2*x2-2*x2-6;do{scanf("%d%d",x1,x2);}while(f1*f2>0);
do
{x=(x1+x2)/2;f=x*x*x-3*x*x-2*x-6;if(f*f1<0){x2=x;f2=f;}
if(f*f2<0)
{x1=x;f1=f;}
}while(fabs(x1-x2)>0.001);
printf("%d",x);}