Java 数组常用函数(2)

package Mat;

public class Matrix {
     
	//打印boolean数组，空格表示false,*表示true
	//前置条件：有一个二维boolean数组
	//后置条件：以矩阵形式进行图形显示
	public static void printBoolMatrix(boolean array[][]) {
     
		int rowLength = array[0].length;
		int couLength = array.length;
		for(int i=0;i != couLength;i++) {
     
			for(int j=0;j != rowLength;j++) {
     
				if(array[i][j] == true) 
					System.out.print("*"+" ");
				else
					System.out.print(" "+" ");
			}
			System.out.print("\n");
		}
	}
	//编写一个matrix库
	//向量点承
	//前置条件：有两个一维数组
	//后置条件：返回一个点承值
	public static double dotVector(double[] a,double[] b) {
     
		double Dot = 0.0;
		for(int i=0;i != a.length;i++) {
     
			Dot += a[i]*b[i];
		}
		return Dot;
	}
	//编写一个matrix库
	//矩阵转置
	public static double[][] transMatrix(double[][] a){
     
		int couLength = a.length;
		int rowLength = a[0].length;
		double[][] c = new double[rowLength][couLength];
		for(int i=0;i != couLength;i++) {
     
			for(int j=0;j != rowLength;j++) {
     
				c[j][i] = a[i][j];
			}
		}
		return c;
	}
	//编写一个matrix库
	//矩阵和矩阵相乘
	//前置条件：有两个数组
	//后置条件：返回一个数组为两个矩阵之积
	public static double[][] multMatrix(double[][] a,double[][] b){
     
		int couLength_a = a.length;
		int couLength_b = b.length;
		int rowLength_a = a[0].length;
		int rowLength_b = b[0].length;
		
		if(rowLength_a != couLength_b)
			return null;
		
		double[][] b_trans = transMatrix(b);
		double[][] result = new double[couLength_a][rowLength_b];
		
		for(int i=0;i != couLength_a;i++) {
     
			for(int j=0;j != rowLength_b;j++) {
     
				result[i][j] = dotVector(a[i], b_trans[j]);
			}
		}
		return result;
	}
	
	//编写一个matrix库
	//矩阵和向量的积
	//前置条件：有一个二维数组，有一个一维数组
	//后置条件：返回一个一维数组
	public static double[] multMatVec(double[][] a,double[] b) {
     
		int couLength = a.length;
		if(a[0].length != b.length)
			return null;
		double[] c = new double[b.length];
		for(int i=0;i != couLength; i++) {
     
			c[i] = dotVector(a[i], b);
		}
		return c;
	}
	//编写一个matrix库
	//向量和矩阵的积
	//前置条件：有一个二维数组，有一个一维数组
	//后置条件：返回一个一维数组
	public static double[] multVecMat(double[][] a,double[] b) {
     
		int couLength = a.length;
		int rowLength = a[0].length;
		
		double[] c = new double[b.length];
		double[][] aTrans = transMatrix(a);
		
		if(couLength != b.length)
			return null;
		
		for(int i=0;i != rowLength; i++) {
     
			c[i] = dotVector(aTrans[i], b);
		}
		
		return c;
		
	}
	
	public static void main(String[] args) {
     
		boolean boolTest[][] ={
     {
     true,false,true},
				{
     false,true,true}};
		printBoolMatrix(boolTest);

	}

}