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FYReader/app/src/main/java/xyz/fycz/myreader/ai/MatrixUtil.java

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8.3 KiB

package xyz.fycz.myreader.ai;
/**
* @author fengyue
* @date 2021/4/7 16:10
*/
public class MatrixUtil {
//矩阵加法 C=A+B
public static double[][] add(double[][] m1, double[][] m2) {
if (m1 == null || m2 == null ||
m1.length != m2.length ||
m1[0].length != m2[0].length) {
return null;
}
double[][] m = new double[m1.length][m1[0].length];
for (int i = 0; i < m.length; ++i) {
for (int j = 0; j < m[i].length; ++j) {
m[i][j] = m1[i][j] + m2[i][j];
}
}
return m;
}
public static double[][] add(double[][] m, double a) {
if (m == null) {
return null;
}
double[][] retM = new double[m.length][m[0].length];
for (int i = 0; i < retM.length; ++i) {
for (int j = 0; j < retM[i].length; ++j) {
retM[i][j] = m[i][j] + a;
}
}
return retM;
}
public static double[][] sub(double[][] m1, double[][] m2) {
if (m1 == null || m2 == null ||
m1.length != m2.length ||
m1[0].length != m2[0].length) {
return null;
}
double[][] m = new double[m1.length][m1[0].length];
for (int i = 0; i < m.length; ++i) {
for (int j = 0; j < m[i].length; ++j) {
m[i][j] = m1[i][j] - m2[i][j];
}
}
return m;
}
//矩阵转置
public static double[][] transpose(double[][] m) {
if (m == null) return null;
double[][] mt = new double[m[0].length][m.length];
for (int i = 0; i < m.length; ++i) {
for (int j = 0; j < m[i].length; ++j) {
mt[j][i] = m[i][j];
}
}
return mt;
}
//矩阵相乘 C=A*B
public static double[][] dot(double[][] m1, double[][] m2) {
if (m1 == null || m2 == null || m1[0].length != m2.length)
return null;
double[][] m = new double[m1.length][m2[0].length];
for (int i = 0; i < m1.length; ++i) {
for (int j = 0; j < m2[0].length; ++j) {
for (int k = 0; k < m1[i].length; ++k) {
m[i][j] += m1[i][k] * m2[k][j];
}
}
}
return m;
}
//数乘矩阵
public static double[][] dot(double[][] m, double k) {
if (m == null) return null;
double[][] retM = new double[m.length][m[0].length];
for (int i = 0; i < m.length; i++) {
for (int j = 0; j < m[0].length; j++) {
retM[i][j] = m[i][j] * k;
}
}
return retM;
}
//同型矩阵除法
public static double[][] divide(double[][] m1, double[][] m2) {
if (m1 == null || m2 == null ||
m1.length != m2.length ||
m1[0].length != m2[0].length) {
return null;
}
double[][] retM = new double[m1.length][m1[0].length];
for (int i = 0; i < retM.length; ++i) {
for (int j = 0; j < retM[i].length; ++j) {
retM[i][j] = m1[i][j] / m2[i][j];
}
}
return retM;
}
//矩阵除数
public static double[][] divide(double[][] m, double k) {
if (m == null) return null;
double[][] retM = new double[m.length][m[0].length];
for (int i = 0; i < m.length; i++) {
for (int j = 0; j < m[0].length; j++) {
retM[i][j] = m[i][j] / k;
}
}
return retM;
}
//求矩阵行列式(需为方阵)
public static double det(double[][] m) {
if (m == null || m.length != m[0].length)
return 0;
if (m.length == 1)
return m[0][0];
else if (m.length == 2)
return det2(m);
else if (m.length == 3)
return det3(m);
else {
int re = 0;
for (int i = 0; i < m.length; ++i) {
re += (((i + 1) % 2) * 2 - 1) * det(companion(m, i, 0)) * m[i][0];
}
return re;
}
}
//求二阶行列式
public static double det2(double[][] m) {
if (m == null || m.length != 2 || m[0].length != 2)
return 0;
return m[0][0] * m[1][1] - m[1][0] * m[0][1];
}
//求三阶行列式
public static double det3(double[][] m) {
if (m == null || m.length != 3 || m[0].length != 3)
return 0;
double re = 0;
for (int i = 0; i < 3; ++i) {
int temp1 = 1;
for (int j = 0, k = i; j < 3; ++j, ++k) {
temp1 *= m[j][k % 3];
}
re += temp1;
temp1 = 1;
for (int j = 0, k = i; j < 3; ++j, --k) {
if (k < 0) k += 3;
temp1 *= m[j][k];
}
re -= temp1;
}
return re;
}
//求矩阵的逆(需方阵)
public static double[][] inv(double[][] m) {
if (m == null || m.length != m[0].length)
return null;
double A = det(m);
double[][] mi = new double[m.length][m[0].length];
for (int i = 0; i < m.length; ++i) {
for (int j = 0; j < m[i].length; ++j) {
double[][] temp = companion(m, i, j);
mi[j][i] = (((i + j + 1) % 2) * 2 - 1) * det(temp) / A;
}
}
return mi;
}
//求方阵代数余子式
public static double[][] companion(double[][] m, int x, int y) {
if (m == null || m.length <= x || m[0].length <= y ||
m.length == 1 || m[0].length == 1)
return null;
double[][] cm = new double[m.length - 1][m[0].length - 1];
int dx = 0;
for (int i = 0; i < m.length; ++i) {
if (i != x) {
int dy = 0;
for (int j = 0; j < m[i].length; ++j) {
if (j != y) {
cm[dx][dy++] = m[i][j];
}
}
++dx;
}
}
return cm;
}
//生成全为0的矩阵
public static double[][] zeros(int rows, int cols){
return new double[rows][cols];
}
//生成全为1的矩阵
public static double[][] ones(int rows, int cols){
return add(zeros(rows, cols), 1);
}
public static double sum(double[][] matrix){
double sum = 0;
for (double[] doubles : matrix) {
for (double aDouble : doubles) {
sum += aDouble;
}
}
return sum;
}
public static double[][] pow(double[][] matrix, int exponent){
if (matrix == null) return null;
double[][] retM = new double[matrix.length][matrix[0].length];
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[i].length; j++) {
retM[i][j] = Math.pow(matrix[i][j], exponent);
}
}
return retM;
}
public static double[][] sqrt(double[][] matrix){
if (matrix == null) return null;
double[][] retM = new double[matrix.length][matrix[0].length];
for (int i = 0; i < matrix.length; i++) {
for (int j = 0; j < matrix[i].length; j++) {
retM[i][j] = Math.sqrt(matrix[i][j]);
}
}
return matrix;
}
public static double[][] to2dMatrix(double[] vector, boolean isCol){
if (vector == null) return null;
double[][] retM;
if (isCol) {
retM = new double[vector.length][1];
}else {
retM = new double[1][vector.length];
}
for (int i = 0; i < vector.length; i++) {
if (isCol) {
retM[i][0] = vector[i];
}else {
retM[0][i] = vector[i];
}
}
return retM;
}
public static double[] toVector(double[][] matrix){
double[] retV = null;
if (matrix.length == 1){
retV = new double[matrix[0].length];
double[] doubles = matrix[0];
System.arraycopy(doubles, 0, retV, 0, doubles.length);
}else if (matrix[0].length == 1){
retV = new double[matrix.length];
for (int i = 0; i < matrix.length; i++) {
retV[i] = matrix[i][0];
}
}
return retV;
}
}