基本矩阵运算的Java实现

基本矩阵运算的Java实现

分类： 图像处理2012-09-18 10:36 2537人阅读 评论(3) 收藏 举报

javamatrixparametersstringclassnull

一： 矩阵的加法与减法

规则：矩阵的加法与减法要求两个矩阵的行列完全相等，方可以完成两个矩阵的之间的运算。

举例说明如下

二：矩阵的乘法

规则：矩阵的乘法要求两个矩阵符合A(mx k),  B( k x n)即矩阵A的列数与矩阵B的行数相等，否

则无法完成矩阵运算。举例说明如下：

Java代码如下：

 package pet.shop;

 public class BasicMatrixMath {
     public final static int OPERATION_ADD = 1;
     public final static int OPERATION_SUB = 2;
     public final static int OPERATION_MUL = 4;

     /**
      * To be able to add two matrices, they must be of the same size
      * @param matrixa
      * @param matrixb
      */
     public int[][] add(int[][] matrixa, int[][] matrixb) {
         if(legalOperation(matrixa, matrixb, OPERATION_ADD)) {
             for(int i=0; i<matrixa.length; i++) {
                 for(int j=0; j<matrixa[0].length; j++) {
                     matrixa[i][j] = matrixa[i][j] + matrixb[i][j];
                 }
             }
         }
         return matrixa;
     }

     /**
      * To be able to substract two matrices, they must be of the same size
      *
      * @param matrixa
      * @param matrixb
      */
     public int[][] substract(int[][] matrixa, int[][] matrixb) {
         if(legalOperation(matrixa, matrixb, OPERATION_SUB)) {
             for(int i=0; i<matrixa.length; i++) {
                 for(int j=0; j<matrixa[0].length; j++) {
                     matrixa[i][j] = matrixa[i][j] - matrixb[i][j];
                 }
             }
         }
         return matrixa;
     }

     /**
      *
      * @param matrixa
      * @param matrixb
      */
     public int[][] multiplication(int[][] matrixa, int[][] matrixb) {
         if(legalOperation(matrixa, matrixb, OPERATION_SUB)) {
             int[][] result = new int[matrixa.length][matrixb[0].length];
             for(int i=0; i<matrixa.length; i++) {
                 for(int j=0; j<matrixb[0].length; j++) {
                     // i will complete this tomorrow @2012/09/17
                     result[i][j] = calculateSingleResult(matrixa, matrixb, i, j);
                 }
             }
             return result;
         }
         else
         {
             return null;
         }
     }

     private int calculateSingleResult(int[][] matrixa, int[][] matrixb, int row, int col) {
         int result = 0;
         for(int k=0; k<matrixa[0].length; k++) {
             result += matrixa[row][k] * matrixb[k][col];
         }
         return result;
     }

     /**
      *
      * @param matrixa
      * @param b
      */
     public int[][] multiplication(int[][] matrixa, int b) {
         for(int i=0; i<matrixa.length; i++) {
             for(int j=0; j<matrixa[0].length; j++) {
                 matrixa[i][j] = matrixa[i][j] * b;
             }
         }
         return matrixa;
     }

     /**
      * validate whether the parameters is valid parameters.
      *
      * @param a
      * @param b
      * @param type
      * @return
      */
     private boolean legalOperation(int[][] a, int[][] b, int type) {
         boolean legal = true;
         if(type == OPERATION_ADD || type == OPERATION_SUB)
         {
             if(a.length != b.length || a[0].length != b[0].length) {
                 legal = false;
             }
         }
         else if(type == OPERATION_MUL)
         {
             if(a[0].length != b.length) {
                 legal = false;
             }
         }
         return legal;
     }

     /**
      *  test code here !!!!
      * @param args
      */
     public static void main(String[] args) {
         int[][] a = new int[][]{{1,2},{3,4}};
         int[][] b = new int[][]{{7, 8}, {6, 5}};
         BasicMatrixMath bmm = new BasicMatrixMath();

         System.out.println("addition two matrix");
         int[][] result = bmm.add(a, b);
         for(int i=0; i<result.length; i++) {
             for(int j=0; j<result[0].length; j++) {
                 System.out.print("\t" + result[i][j]);
             }
             System.out.println();
         }

         System.out.println("substract two matrix");
         result = bmm.substract(a, b);
         for(int i=0; i<result.length; i++) {
             for(int j=0; j<result[0].length; j++) {
                 System.out.print("\t" + result[i][j]);
             }
             System.out.println();
         }

         System.out.println("multiplex one matrix");
         result = bmm.multiplication(a, 3);
         for(int i=0; i<result.length; i++) {
             for(int j=0; j<result[0].length; j++) {
                 System.out.print("\t" + result[i][j]);
             }
             System.out.println();
         }

         System.out.println("multiplex two matrix");
         result = bmm.multiplication(a, b);
         for(int i=0; i<result.length; i++) {
             for(int j=0; j<result[0].length; j++) {
                 System.out.print("\t" + result[i][j]);
             }
             System.out.println();
         }
     }
 }