Given two vectors A and B, the dot product of the two vectors (A dot B) gives the product ABcos(ang), so to get just the angle, you want to take the dot product of two unit vectors;
Assume A = [ax, ay, az], B = [bx, by, bz]
magA = sqrt(ax^2+ay^2+az^2); % = sqrt(A(1)^2 + A(2)^2 + A(3)^2)
magB = sqrt(bx^2+by^2+bz^2); % = sqrt(B(1)^2 + B(2)^2 + B(3)^2)
UA = [ax/magA, ay/magA, az/magA]; % A unit vector, = [A(1)/magA, A(2)/magA, A(3)/magA]
UB = [bx/magB, by/magB, bz/magB]; % B unit vector, = [B(1)/magB, B(2)/magB, B(3)/magB]
cosAng = dot(UA,UB); % = UA(1)*UB(1) + UA(2)*UB(2) + UA(3)*UB(3)
ang = acos(cosang); % This is the angle between vector A and Vector B, in radians
As a function;
function ang = Vangle(A,B)
magA = sqrt(A(1)^2 + A(2)^2 + A(3)^2);
magB = sqrt(B(1)^2 + B(2)^2 + B(3)^2);
UA = [A(1)/magA, A(2)/magA, A(3)/magA]
UB = [B(1)/magB, B(2)/magB, B(3)/magB]
cosAng = UA(1)*UB(1) + UA(2)*UB(2) + UA(3)*UB(3);
ang = acos(cosang);
return
end
