syms x l1 l2 l3; 改为 syms x v l1 l2 l3;[V,D] = eig(A) 改为 u=inv(A)
你下面这一句的v未定义: A=[a11-1.362*v^2, a12,a13; a12, a22-1.362*v^2, a23; a13, a23, a33-1.362*v^2]