public void testSlice() {
DenseMatrix A = rand(5, 8);
DenseMatrix B = rand(5, 12);
DenseMatrix C = rand(4, 8);
DenseMatrix AB = A.concatRight(B);
assertTrue(A.equals(AB.cols(0, 8)));
assertTrue(B.equals(AB.cols(8, 20)));
DenseMatrix AC = A.concatDown(C);
assertTrue(A.equals(AC.rows(0, 5)));
assertTrue(C.equals(AC.rows(5, 9)));
}
