U = [4/5, 3/5, 0  ; ...
     0  , 4/5, 3/5; ...
     3/5, 0  , 4/5 ];

S = [ 1, 0, 0;
      0, 2, 0;
      0, 0, 3 ];

V = [ 0, 1, 0;
      1, 0, 0;
      0, 0, 1 ];

A = U*S*V';

expected = A;
actual = rank_k_approximation(A, 3);

unit_test_equals("Full rank approximation of a matrix is itself", ...
		 expected, ...
		 actual);
