Solutions to under-constrained linear system

linear_system.matlab

>> rng(0)
>> A=randi(10, 2, 5); b=randi(100, 2, 1);

% A =                                 b =
%      9     7     8     7     8            28
%     10     8     4     2     1            5

>> x1=A\b; x2=pinv(A)*b

% x1 =                x2 =
%          0              1.5675
%    10.2500              6.1976
%          0             -3.8780
%          0              2.5279
%    -0.4500              0.9060

>> b1=A*x1; b2=A*x2;

% b1 =                b2 = 
%    16.0000             16.0000
%    98.0000             98.0000