public int findPoint(){
        int i=1;
        while(f(i) <=0 ){
            i = i*2;
        }
        return binarySearch(i/2,i);
    }
http://www.geeksforgeeks.org/find-the-point-where-a-function-becomes-negative/
src/com/interview/binarysearch/MonotonicallyIncreasingFunctionBecomesPositive.java