开发了一个比较通用的矩阵计算静态方法库。
用以计算矩阵的点乘与叉乘，矩阵与列向量的乘积，列向量与矩阵的乘积，矩阵的转置。。。
分为Java与.NET C# 两个版本。
以下为各部分源码（各自包含测试的主函数）；
Java：
package MatrixPackage;
public class Matrix {
public static double dot(double[] x, double[] y) {
if (x.length == y.length) {
double result = 0d;
for (int i = 0; i < x.length; i++) {
result += x[i] * y[i];
}
return result;
} else {
return Double.MAX_VALUE;
}
}
public static double[][] mult(double[][] x, double[][] y) {
if (x[0].length == y.length) {
double[][] result = new double[x.length][y[0].length];
for (int i = 0; i < x.length; i++) {
for (int k = 0; k < y[0].length; k++) {
double sum = 0;
for (int j = 0; j < y.length; j++) {
sum += x[i][j] * y[j][k];
}
result[i][k] = sum;
}
}
return result;
} else {
return null;
}
// x[0].length 列数
}
public static double[][] transpose(double[][] x) {
int row = x.length;
int col = x[0].length;
double[][] res = new double[col][row];
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++) {
res[j][i] = x[i][j];
}
}
return res;
}
public static double[][] mult(double[][] a, double[] x) {
if (a[0].length == x.length) {
double[][] res = new double[a.length][1];
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < x.length; j++) {
res[i][0] += a[i][j] * x[j];
}
}
return res;
} else {
return null;
}
}
public static double[] mult(double[] y, double[][] a) {
if (y.length == a.length) {
double[] res = new double[a[0].length];
for (int i = 0; i < a[0].length; i++) {
double sun = 0;
for (int j = 0; j < a.length; j++) {
sun += a[j][i] * y[j];
}
res[i] = sun;
}
return res;
} else {
return null;
}
}
}
测试主函数：
package Test;
import MatrixPackage.Matrix;
public class TestDemo {
public static void main(String[] args) {
try {
double[][] a = {
{
1, 2, 3, 4 }, {
4, 5, 6, 8 }, {
7, 8, 9, 20 } };
double[][] b = {
{
4, 5, 6, 8, 9 }, {
4, 5, 6, 8, 9 }, {
4, 5, 6, 8, 6 }, {
4, 5, 6, 8, 3 } };
double[] d = {
1, 2, 3 };
double[] c = Matrix.mult(d, a);
// for (int i = 0; i < c.length; i++) {
// for (int j = 0; j < c[0].length; j++) {
// System.out.print(c[i][j] + " ");
// }
// System.out.println();
// }
for (int i = 0; i < c.length; i++) {
System.out.print(c[i] + " ");
}
//System.out.println(c.length);
} catch (Exception e) {
System.out.println(e.getMessage());
}
}
}
.NET C#：
using System;
namespace Matrix
{
public class MatrixLib
{
public static double dot(double[] x, double[] y)
{
if (x.Length == y.Length)
{
double result = 0d;
for (int i = 0; i < x.Length; i++)
{
result += x[i] * y[i];
}
return result;
}
else
{
return Double.NaN;
}
}
public static double[,] mult(double[,] x, double[,] y)
{
if (x.GetLength(1)== y.GetLength(0))
{
double[, ] result = new double[x.GetLength(0), y.GetLength(1)];
for (int i = 0; i < x.GetLength(0); i++)
{
for (int k = 0; k < y.GetLength(1); k++)
{
double sum = 0;
for (int j = 0; j < y.GetLength(0); j++)
{
sum += x[i,j] * y[j,k];
}
result[i,k] = sum;
}
}
return result;
}
else
{
return null;
}
}
public static double[,] transpose(double[,] x)
{
int row = x.GetLength(0);
int col = x.GetLength(1);
double[,] res = new double[col,row];
for (int i = 0; i < row; i++)
{
for (int j = 0; j < col; j++)
{
res[j,i] = x[i,j];
}
}
return res;
}
public static double[,] mult(double[,] a, double[] x)
{
if (a.GetLength(1) == x.Length)
{
double[,] res = new double[a.GetLength(0),1];
for (int i = 0; i < a.GetLength(0); i++)
{
for (int j = 0; j < x.Length; j++)
{
res[i,0] += a[i,j] * x[j];
}
}
return res;
}
else
{
return null;
}
}
public static double[] mult(double[] y, double[,] a)
{
if (y.Length == a.GetLength(0))
{
double[] res = new double[a.GetLength(1)];
for (int i = 0; i < a.GetLength(1); i++)
{
double sun = 0;
for (int j = 0; j < a.GetLength(0); j++)
{
sun += a[j,i] * y[j];
}
res[i] = sun;
}
return res;
}
else
{
return null;
}
}
}
}
测试主函数：
using System;
using static Matrix.MatrixLib;
namespace MatrixTest
{
class Program
{
static void Main(string[] args)
{
try
{
double[,] a = {
{
1, 2, 3, 4 }, {
4, 5, 6, 8 }, {
7, 8, 9, 20 } };
double[,] b = {
{
4, 5, 6, 8, 9 }, {
4, 5, 6, 8, 9 }, {
4, 5, 6, 8, 6 }, {
4, 5, 6, 8, 3 } };
double[] d = {
1, 2, 3 ,4};
double[] e = {
1, 2, 3 };
double[] c = Matrix.MatrixLib.mult(d,b);
// for (int i = 0; i < c.length; i++) {
// for (int j = 0; j < c[0].length; j++) {
// System.out.print(c[i][j] + " ");
// }
// System.out.println();
// }
for (int i = 0; i < c.GetLength(0); i++)
{
//for (int j = 0;j < c.GetLength(1); j++)
// {
// Console.Write(c[i,j] + " ");
//}
Console.Write(c[i] + " ");
}
Console.WriteLine();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
}
}
不定时更新中，若有更多计算函数，会及时更新。