Question

我正在尝试使用solve方法，但它给了我一个错误，有人可以帮我解决如何编写求解方法吗？我尝试运行此代码，解决方法之前的代码工作正常，但在那之后它给了我一个错误。非常感谢你

import java.lang.Math;
public class MatrixDriver {

  public static void main(String[] args) {
    double[][] d = { { 1, 2, 3 }, { 4, 5, 6 }, { 9, 1, 3} };

     System.out.println("Matrix D - Testing Constructor that take double integer array as a parameter");
    Matrix D = new Matrix(d);
    System.out.println(D);
    System.out.println();

    System.out.println("Matrix A - Testing Named Constructor -- random\nTakes two parameters (row, col) and returns a \"new\" Matrix");
    Matrix A = Matrix.random(5, 5);
    System.out.println(A);
    System.out.println();

    System.out.println("Matrix A - Testing the swap rows method");
    A.swapRows(1,2);
    System.out.println(A);
    System.out.println();

    System.out.println("Matrix B - Testing the transpose method on Matrix A");
    Matrix B = A.transpose();
    System.out.println(B);
    System.out.println();

    System.out.println("Matrix C - Testing named constructor - identity - which takes a single parameter (i) and returns a 'new' (i x i) Identity Matrx");
    Matrix C = Matrix.identity(5);
    System.out.println(C);
    System.out.println();

    System.out.println("Matrix E - Testing matrix addition (A + B)");
    Matrix E = A.plus(B);
    System.out.println(E);
    System.out.println();

    System.out.println("Matrix F - Testing matrix subtraction (A - B)");
    Matrix F = A.minus(B);
    System.out.println(F);
    System.out.println();

    System.out.println("Matrix G - Testing matrix scalar multiplication (c * A), c = 1.2");
    double c = 1.2;
    Matrix G = A.times(c);
    System.out.println(G);
    System.out.println();

    System.out.println("Matrix AB - Testing matrix multiplication (A X B)");
    Matrix AB = A.times(B);
    System.out.println(AB);
    System.out.println();

  System.out.println("Matrix BA - Testing matrix multiplication (B X A)");
  Matrix BA = B.times(A);
  System.out.println(BA);
  System.out.println();

    System.out.println("Matrices AB and BA - Testing Matrix Equality (AB equals BA)"); 
    try 
    {
      System.out.println("  " + AB.equals(BA));
      System.out.println();
    } 
    catch(RuntimeException e) 
    {
      System.out.println(e.getMessage());
      System.out.println();

    }
  System.out.println("Matrix b - Creating a random (5 X 1)");
  Matrix b = Matrix.random(5,1);
  System.out.println(b);
  System.out.println();

  System.out.println("Matrix X - Testing the solve method (X = A^-1 * b)");
  Matrix L= Matrix.solve(X);
  double X = Math.pow(A,-1) * b;
  //b.solve(b);
  System.out.println(b);
  System.out.println();

  System.out.println("Matrix d - Testing the sove again (A x X) = b ... is it?");
  Matrix b = Matrix.solve();
  System.out.println(b);
  System.out.println();
   }
}

Answer 1

你没有使用JAMA，你正在使用：http://introcs.cs.princeton.edu/java/95linear/Matrix.java.html你呢？这将是下次有用的。

回答你的问题虽然是什么＆＃39; x＆＃39; Matrix.solve的方法并不知道＆＃39; X＆＃39;是。

Matrix L= Matrix.solve(X);
double X = Math.pow(A,-1) * b;

应该是：

double X = Math.pow(A,-1) * b;
Matrix L= Matrix.solve(X);

但是即使这样，你仍然会有错误，因为Math.pow不适用于Matrix，如果你想要^ 2整个矩阵，你需要使用另一种方法。这是：https://stackoverflow.com/a/22901024/4329778

Answer 2

我可以建议这个post。我认为JAMA不再更新，org.apache.commons.math3.linear似乎是当前最先进的矩阵库。在Android Studio中，您可以添加Gradle：

实现'org.apache.commons：commons-math3：3.6.1'

Matrix Solve方法java

2 个答案: