java/algorithms/math/MatrixMultiply.java at master · AllAlgorithms/java · GitHub

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public class MatrixMultiply {

/**

* Multiples 2 2-dimensional matrices together given their dimensions are

* compatible

* @param mat_a A 2-Dimensional matrix to be multiplied

* @param mat_b A 2-Dimensional matrix to be multiplied

* @return The product of the two matrices if compatible dimensions, null

* otherwise

public static double[][] matrixMultiply2D(double[][] mat_a, double[][] mat_b) {

int aRows = mat_a.length;

int aColumns = mat_a[0].length;

int bRows = mat_b.length;

int bColumns = mat_b[0].length;

if (aColumns != bRows)

throw new IllegalArgumentException("A:Rows: " + aColumns + " did not match B:Columns " + bRows + ".");

double[][] mat_result = new double[aRows][bColumns];

for (int i = 0; i < aRows; i++) {

for (int j = 0; j < bColumns; j++) {

mat_result[i][j] = 0.00000;

}

for (int i = 0; i < aRows; i++) { // aRow

for (int j = 0; j < bColumns; j++) { // bColumn

for (int k = 0; k < aColumns; k++) { // aColumn

mat_result[i][j] += mat_a[i][k] * mat_b[k][j];

}

return mat_result;

}

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