Alright well I was out sick for a while and when I came back we had already started our new project. Basically for the first version it just has to find the root (zero) of a function which is set into the code as a variable, given the low and high (also variables). I know I need to use recursion in the root finder method but I was gone for that also so I am not totally clear on it either. Here is what I've wrote so far, I'm kinda stuck on where to go with it, so if anyone could help me out a little it would be greatly appreciated.

Code:
public class main
{
	double t = 0.001; // t represents tolerance
	double Lo = 10;
	double Hi = -10;
	
   public void main()
	{
	   
	 }
	
	double abs(double x)
	{//Pre accepts double x
		//Post returns absolute value
		 if (x >= 0) return x;
		else return (-x);
	}
	
	int sgn (double x)
	{//Pre accepts double x
		//Post returns -1 if negative, 0 if 0, 1 is postive
		if (x > 0){ return 1;}
		   if (x < 0){ return -1;}
			if (x==0){ return 0;}
		} 
	   
	
		
		 
		double f (double x)
		{// f(x)-the function
		   return x-2;
		}
		
		double RootFinder (double Lo, double Hi)
		{
			double Mid = ((Lo + Hi)/2);
			
		   
			if (((sgn(f(Lo)))==(-1)))&&((sgn(f(mid)))==(-1))) RootFinder(mid, Hi);
			if (((sgn(f(mid)))==(1)) && ((sgn(f(Hi))==(1))) RootFinder(Lo, mid);
			if (((sgn(f(mid)))==(1) && ((sgn(f(Hi)))==(-1))) RootFinder(mid, Hi);
		   
			if ((abs(Hi-Lo)) < t) return Mid;
		}