#include "math.h"
int atkn(x,eps,js,f)
int js;
double eps,*x,(*f)();
{ 
	int flag,l;
    double u,v,x0;
    l=0; x0=*x; flag=0;
    while ((flag==0)&&(l!=js))
    { 
		l=l+1; 
        u=(*f)(x0); v=(*f)(u);
        if (fabs(u-v)<eps) 
		{ 
			x0=v; flag=1; 
		}
        else x0=v-(v-u)*(v-u)/(v-2.0*u+x0);
    }
    *x=x0; l=js-l;
    return(l);
}