急，高手帮忙

只看该作者 · 2007-6-11 16:35

这段程序没有编错，可是算不出结果，请指点，屏幕上没有结果。
float f(float x)
{
    float y;
//    y=(((0.54525/1e7-1.2103722/1e10*273.16)*x + 1.4307/1e7*273.16 - 0.75/1e4)*x + 0.57/1e4*273.16)*x-0.7;
    y=(0.54525/1e7-1.2103722/1e10*273.16)*x*x*x + (1.4307/1e7*273.16 - 0.75/1e4)*x*x + (0.57/1e4*273.16)*x;//-0.7;
    return(y);
}
float xpoint(float x1,float x2)
{
    float y;
    y=(x1*f(x2)-x2*f(x1))/(f(x2)-f(x1));
    return(y);
}
float root(float x1,float x2)
{
//    int i;
    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);
}
main()
{
    float x1=0,x2=70,f1,f2,x;
    do
    {
        f1=f(x1);
        f2=f(x2);
    }
    while(f1*f2>=0);
    x=root(x1,x2);
    printf("A root of equation is%f",x);
    while(1);
}