1 double NewtonMethod(double fToBeSqrted) 2 { 3     double x = 1.0; 4     while(abs(x*x-fToBeSqrted) > 1e-5) 5     { 6         x = (x+fToBeSqrted/x)/2; 7     } 8  9     return x;10 }

 1 float get_sqrt(float x) 2 { 3     float low=0, up=x, mid, now; 4     mid=(low+up)/2; 5     do 6     { 7         now=mid;        //**now保存上一次计算的值 8         if(mid*mid<x)   //**mid偏小，右移 9         {10             low=mid;11         }12         else       //**mid偏大，左移13         {14             up=mid;15         }16         mid=(low+up)/2;17     }while(abs(mid-now)>eps); //**两次计算的误差小于eps，mid即为所求值18     return mid;19 }