import de.jungblut.math.dense.DenseDoubleMatrix; import de.jungblut.math.dense.DenseDoubleVector; DenseDoubleMatrix matrix = new DenseDoubleMatrix(3, 3); matrix.set(0, 0, 1.0); matrix.set(0, 1, 2.0); matrix.set(0, 2, 3.0); DenseDoubleMatrix transposedMatrix = matrix.transpose(); DenseDoubleMatrix productMatrix = matrix.multiply(transposedMatrix);