u=[1;5;6;7]
v=[8 6 5]
A=[1 2 3; 4 5 6; 7 8 9]
B=[1 4 7 10; 2 5 8 11; 3 6 9 12]
[nLu nCu] = size(u)
[nLv nCv] = size(v')
[nLA nCA] = size(A')
[nLB nCB] = size(B)
if nCv==nLA then
    x = v'*A'
    if nCB==nLu then
        y = B*u
        [nLx nCx] = size(x)
        [nLy nCy] = size(y)
        if nCx==nLy then
            disp("coerente", x*y)
        else
            disp("incoerente 3")
        end
    else
        disp("incoerente 2")
    end
else
    disp("incoerente 1")
end