function alpha = calcula_coefs_aproximacao(M,Minv,b)

alpha = Minv*b;
r = b - M*alpha;
residuo_L2 = norm(r,2);
residuo_Linf = norm(r,inf);
fprintf(2,'norma do residuo do sistema = %9.6f (L2) %9.6f (Linf)\n',...
    residuo_L2,residuo_Linf);