Expanding Rods

http://poj.org/problem?id=1

 #include<cstdio>
 #include<cstring>
 #include<cmath>
 #include<algorithm>
 using namespace std;

 const double eps=1e-;
 double n,c,l;

 int main()
 {
     while(scanf("%lf%lf%lf",&l,&n,&c)&&l!=-&&n!=-&&c!=-){
         double s=(+n*c)*l;
         double low=,high=0.5*l,mid;
         while(high-low>eps)
         {
             mid=(high+low)/;
             double r=(*mid*mid+l*l)/(*mid);
             double ss=*r*asin(l/(*r));
             if(ss<s)
                 low=mid;
             else
                 high=mid;
         }
         printf("%.3lf\n",mid);
     }
     return ;
 }