多维数组逐行乘以
多维数组逐行乘以
提问于 2013-02-14 06:45:12
我在java中有以下数组，我想用array_x列乘以array_y行来最终创建array_z值
aray_x array_y array_z
4|9 4|11|12|14 |
--- ---------- -----
8|7 13|9|22|7 |
--- -----
3|2 |
--- -----
9|1 | 我的试用代码列出了公共类乘法{
public static void main(String[] args) {
int array_x[][] = {{9, 8}, {2, 17}, {49, 4}, {13, 119}, {2, 19}, {11, 47}, {3, 73}};
int[][] array_y = new int[][]{{4, 11, 12, 14}, {13, 9, 22, 7}};
int array_z[][] = new int[4][2];
for (int i = 0; i < array_x.length; i++) {
for (int j = 0; j < array_x.length; j++) {
array_z[i][j] = array_x[i][j] * array_y[j][i];
System.out.print(" "+array_z[i][j]);
}
}
}}
如何实现这个-那；array_z的第1列由array_x的第1列和array_y的第1行的倍数填充。例如4x4=16，8x11=88，thius array_x * array_y =array_z array_z的第2列由array_x的第2列和array_y的第2行的倍数填充。
回答 2
Stack Overflow用户
回答已采纳
发布于 2013-02-14 07:22:21
下面是一个要编译和运行的完整类，其中包含您的数据...希望这能有所帮助
public class Alphy {
private double[][] x;
public Alphy (double[][] x) {
this.x = x;
}
public double[][] multiplyWith (double[][] y) {
int nr = x.length, nc = x[0].length;
double[][] z = new double[nr][nc];
for (int i = 0 ; i < nr ; i++)
for (int j = 0 ; j < nc ; j++)
z[i][j] = x[i][j] * y[j][i];
return z;
}
public static void print (double[][] m, String label) {
int nr = m.length, nc = m[0].length;
System.out.println (label);
for (int i = 0 ; i < nr ; i++) {
for (int j = 0 ; j < nc ; j++)
System.out.print ("\t" + m[i][j]);
System.out.println();
}}
public static void main (String[] args) {
double[][] X = {{4, 9}, {8, 7}, {3, 2}, {9, 1}},
Y = {{4, 11, 12, 14}, {13, 9, 22, 7}},
Z = new Alphy(X).multiplyWith(Y);
Alphy.print (X, "Initial Matrix");
Alphy.print (Y, "Multiplied by");
Alphy.print (Z, "Gives the result");
}}
/* Output of the above class:
Initial Matrix
4.0 9.0
8.0 7.0
3.0 2.0
9.0 1.0
Multiplied by
4.0 11.0 12.0 14.0
13.0 9.0 22.0 7.0
Gives the result
16.0 117.0
88.0 63.0
36.0 44.0
126.0 7.0
*/Stack Overflow用户
发布于 2013-02-14 08:51:24
我的数学有点生疏，但这是正确的答案吗？
int array_x[][] = {{4, 9}, {8, 7}, {3, 2}, {9, 1}};
int array_y[][] = {{4, 11, 12, 14}, {13, 9, 22, 7}};
int array_z[][] = new int[array_x[0].length][array_y.length];
for (int i = 0; i < array_x[0].length; i++) {
for (int j = 0; j < array_y.length; j++) {
if (array_x.length != array_y[i].length) {
System.out.println("Dimention missmatch " + array_x.length +" vs "+ array_y[i].length);
System.exit(-1);
}
int sum = 0;
for (int k = 0; k < array_x.length; k++) {
sum += array_x[k][i] * array_y[j][k];
// System.out.println(i+"\t"+ j +"\t"+k+"\t"+ array_x[k][i] +"\t"+ array_y[j][k] +"\t"+ sum+"\t");
}
// System.out.println();
array_z[i][j] = sum;
}
}
System.out.println(Arrays.deepToString(array_z));输出：
[[266, 253], [151, 231]]或者您需要一个4X4矩阵作为结果？
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/14864700
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