%% SL20
A = [-1 1; 1 -2]
B = [1 2 3; 4 5 6; 7 8 9]

%% SL25
a = 3.24; alpha = pi/7;
a*sin(alpha)^2 + a*cos(alpha)^2 - a

a = 14; b = 28;
log10(a) + log10(b) - log10(a*b)

T = [1/2 1/3 1/4 1/5; 6 7 8 9; 0.2 0.3 0.4 0.5];
sum(T, 2)

%% SL26
u = [1 2 3]; v = [3 2 1];
u*transpose(v), v * transpose(u)
v.'*u, u.'*v
dot(u, v), cross(u, v)