Printing out: no solution, multiple solution with Apache in java

Question

I have this code which give solution to 4x4 linear equations. how can i print out when a linear equation have no solution or have multiples ones. instead of prints error ?

public class OvaWork 
{


    void fourthEquationSolver()
    {
        //Creating  Arrays Representing Equations
        double[][] lhsArray = {{8,1,10,1}, {2,1,5,4}, {1,5,3,2}, {9,8,4,6}};
        double[] rhsArray = {14,22,38,44};
        //Creating Matrix Objects with arrays
        Matrix lhs = new Matrix(lhsArray);
        Matrix rhs = new Matrix(rhsArray, 4);
        //Calculate Solved Matrix
        Matrix ans = lhs.solve(rhs);
        //Printing Answers
        System.out.println("x1 = " + (ans.get(0, 0)));
        System.out.println("x2 = " + (ans.get(1, 0)));
        System.out.println("X3 = " + (ans.get(2, 0)));
        System.out.println("X4 = " + (ans.get(3, 0)));
    }



    public static void main(String[] args) 
    {
        OvaWork equation = new OvaWork();

    }
}

When i write into this code a matrix like this:

1,1,1,1=14
2,2,2,2=22
3,3,3,3=38
4,4,4,4=44

this code prints :

Exception in thread "main" java.lang.RuntimeException: Matrix is singular.
    at Jama.LUDecomposition.solve(LUDecomposition.java:282)
    at Jama.Matrix.solve(Matrix.java:815)
    at OvaWork.fourthEquationSolver(OvaWork.java:20)
    at OvaWork.main(OvaWork.java:106)

because the above matrix have or multiple solutions, or no have solution

So, change your code to do that. BTW: Did you notice that you clicked a button called "**Ask Question**" when you wrote your text here? I don't see any question in your text. — Andreas, Apr 28 '16 at 14:36
@Andreas I'm asking question about how to print out when a linear equation implemented in my code have no soution or have multiple ones. cuz till now, my code just print out when have just one solution. — Volazh, Apr 28 '16 at 14:41
Please could you describe the error you are getting, as it is difficult to help answer your question otherwise. — jr593, Apr 28 '16 at 14:44

Troncador · Accepted Answer · 2016-04-28T14:58:02.187

0

You can ask for the determinant https://en.wikipedia.org/wiki/Determinant

"A system of linear equations has a unique non-trivial solution if and only if its determinant is non-zero. If this determinant is zero, then the system has either no nontrivial solutions or an infinite number of solutions."

http://math.oregonstate.edu/home/programs/undergrad/CalculusQuestStudyGuides/vcalc/system/system.html

if (lhs.det() == 0) {
    System.out.println("No solution or infinite number of solutions");
} else {
    Matrix ans = lhs.solve(rhs);
    //Printing Answers
    System.out.println("x1 = " + (ans.get(0, 0)));
    System.out.println("x2 = " + (ans.get(1, 0)));
    System.out.println("X3 = " + (ans.get(2, 0)));
    System.out.println("X4 = " + (ans.get(3, 0)));
}

edited Apr 28 '16 at 14:58

answered Apr 28 '16 at 14:52

Troncador

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very usefull your answer, but can i get a separate ones?. I mean is diferent when i get a no solution than when i get a multiples solutions. (when i get a 0,0,0,x = x) mean there're multiples solution, than when i get a (0,0,0,0 = 0) that's mean that the matix doesn't have solution at all – Volazh Apr 28 '16 at 15:05
You can reduce the matrix to the "row echelon" form, if somes row have only zeros, then there is infinite solutions – Troncador Apr 28 '16 at 15:13
how "row echelon" form looks like implemented in my code? – Volazh Apr 28 '16 at 15:42
humn... I don't know, maybe you have to program it, or find a library. Or maybe there is another matrix property you can use to differentiate it that is beyond my math knowledge :p – Troncador Apr 29 '16 at 02:38

Printing out: no solution, multiple solution with Apache in java

1 Answers1