integeration

AreaUnderCurve.java

package test.areaundercurve;

public class AreaUnderCurve {

    public double getAreaUnderCurve(Term[] equation, int limit1, int limit2){
      double ret =0.0;  
      if(limit1 == limit2) return ret;  //when limits are equal the area under the curve is equal
        
  //Write your code here
        int i;      
        
        Term[] res = new Term[equation.length]; //stores the equation after integeration
        double lim1Res = 0.0; // stores the result after applying lower limit
        double lim2Res = 0.0; // stores the result after applying upper limit
        
        // finding the integeration
        for(i = 0; i < equation.length; ++i){
          res[i] = new Term(equation[i].x_pow + 1, equation[i].coeff / (equation[i].x_pow + 1));
        }
        
        //applying the limit
        for(i = 0; i < equation.length; ++i){
          lim1Res += Math.pow(limit1, res[i].x_pow) * res[i].coeff;
          lim2Res += Math.pow(limit2, res[i].x_pow) * res[i].coeff;
        }
        
        ret = (double)Math.round((lim2Res - lim1Res) * 10000) / 10000;
        return ret;
    }
 //  You could use this sample code to test your functions
    //  Following main fucntion contains 3 representative test cases
    public static void main(String[] args) {
        //TestCase 1
        try{
            AreaUnderCurve algo = new AreaUnderCurve();
            Term[] func = new Term[2];
            func[0] = new Term(1, 1);
            func[1] = new Term(2, 3);
            int limit1 = 4;
            int limit2 = 8;
            System.out.println(algo.getAreaUnderCurve(func, limit1, limit2));
        }
        catch(Exception e){
            e.printStackTrace();
        }
        //TestCase 2
        try{
            AreaUnderCurve algo = new AreaUnderCurve();
            Term[] func = new Term[1];
            func[0] = new Term(1, 1);                
            int limit1 = 1;
            int limit2 = 1;
            System.out.println(algo.getAreaUnderCurve(func, limit1, limit2));
        }
        catch(Exception e){
            e.printStackTrace();
        }
        //TestCase 3
        try{
            AreaUnderCurve algo = new AreaUnderCurve();
            Term[] func = new Term[1];
            func[0] = new Term(1, 1);
            int limit1 = 2;
            int limit2 = 1;
            System.out.println(algo.getAreaUnderCurve(func, limit1, limit2));
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }
}

Term.java

package test.areaundercurve;

public class Term {
    public double coeff;
    public int x_pow;


    public Term(int x_power, double coefficient) {
        x_pow = x_power;
        coeff = coefficient;
    }
}