Jama软件包，4x4线性方程求解器

Question

我试图用Jama来求解一个4x4线性方程组(4个变量，4个方程)。我尝试过以下代码，但它不起作用。如果有人能帮助我，使用Jama或其他任何方法，我将不胜感激。

import Jama.Matrix;

public class OvaWork {

    public OvaWork() 
    {

        //Creating  Arrays Representing Equations
        double[][] lhsArray = {{-3, 1, -1}, {5, -2, 1}, {-1, 1, 3}, {2, 5, 7}};
        double[] rhsArray = {-4, 6, 0, 8};
        //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("w = " + Math.round(ans.get(0, 0)));
        System.out.println("x = " + Math.round(ans.get(1, 0)));
        System.out.println("y = " + Math.round(ans.get(2, 0)));
        System.out.println("z = " + Math.round(ans.get(3, 0)));
    }

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

Answer 1

您必须尝试使用更简单的例子，如2x2方程。

double[][] lhsArray = {{1,1},{2, 0}};
double[] rhsArray = {10,2};
Matrix lhs = new Matrix(lhsArray);
Matrix rhs = new Matrix(rhsArray, 2);
Matrix ans = lhs.solve(rhs);

它工作，输出是一个矩阵{1,9}

代码的问题是矩阵不是正方形的，而是3x4。

double[][] lhsArray = {{-3, 1, -1}, {5, -2, 1}, {-1, 1, 3}, {2, 5, 7}};

把你的矩阵转换成正方形。

测试这个琐碎的等式：

double[][] lhsArray = {{1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, 1}};
double[] rhsArray = {1, 2, 3, 4};
Matrix lhs = new Matrix(lhsArray);
Matrix rhs = new Matrix(rhsArray, 4);
Matrix ans = lhs.solve(rhs);

ans为{1,2,3,4}。