我的弦截法求大神拯救
#include <stdio.h>#include <math.h>
#include <stdlib.h>
float f(float x)
{
float y;
y=((x-5.0)*x+16.0)*x-80.0;
return y;
}
float xpoint(float x1,float x2)
{
float x;
x=(x1*f(x2)-x2*(x1))/(f(x2)-f(x1));
return x;
}
float root(float x1,float x2)
{
float 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)>=0.0001);
return x;
}
int main()
{
float x1,x2,f1,f2,x;
do
{
printf("input x1,x2:\n");
scanf("%f,%f",&x1,&x2);
f1=f(x1);
f2=f(x2);
}
while(f1*f2>=0);
x=root(x1,x2);
printf("A root of equation is %8.4f\n",x);
system("pause");
return 0;
}