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();
        }
    }
}