java/math/MatrixMultiply.java at master · rmnbrgr/java · GitHub

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publicclassMatrixMultiply {

/**
 * 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
 */
publicstaticdouble[][] matrixMultiply2D(double[][] mat_a, double[][] mat_b) {
intaRows = mat_a.length;
intaColumns = mat_a[0].length;
intbRows = mat_b.length;
intbColumns = mat_b[0].length;

if (aColumns != bRows)
thrownewIllegalArgumentException("A:Rows: " + aColumns + " did not match B:Columns " + bRows + ".");

double[][] mat_result = newdouble[aRows][bColumns];
for (inti = 0; i < aRows; i++) {
for (intj = 0; j < bColumns; j++) {
mat_result[i][j] = 0.00000;
 }
 }

for (inti = 0; i < aRows; i++) { // aRow
for (intj = 0; j < bColumns; j++) { // bColumn
for (intk = 0; k < aColumns; k++) { // aColumn
mat_result[i][j] += mat_a[i][k] * mat_b[k][j];
 }
 }
 }
returnmat_result;
	}

}