行列の積 3×3

Javaで行列の積の計算。
3x3の行列のみ。

double[][] mulArray(double[][] A, double[][] B) {
		double[][] C = new double[3][3];
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				double sum = 0;
				for (int k = 0; k < 3; k++) {
					sum += A[i][k] * B[k][j];
				}
				C[i][j] = sum;
			}
		}
		return C;
	}