[1 -1; 1 1] \ [0; 2]
M = [1 2 3; 4 5 6; 7 8 10]; b = [12; 15; 19];
M' \ b
M = [1 -1/3 -1/3 0; -1/2 1 0 -1/2; -1/2 0 1 -1/2; 0 -1/3 -1/3 1];
b = [3 0 0 6]';
reshape(M \ b, [2, 2])
m = hilb(5); b = m * ones(5, 1); x = m \ b;
cond(m)
[min(x) max(x)]
m = hilb(25); b = m * ones(25, 1); x = m \ b;
cond(m)
[min(x) max(x)]
m = hilb(100); b = m * ones(100, 1); x = m \ b;
cond(m)
[min(x) max(x)]