matlab解方程组，答案是sym没有具体数值

clear all
clc

E=2*10^5;
v=0.3;
G=E/(2*(1+v));
lambda=(v*E)/((1+v)*(1-2*v));
epsilon11=1.7833*10^-3;
epsilon22=1.6*10^-3;
syms sigma11 sigma22 epsilon33;

eq1=sym('sigma11=2*G*epsilon11+lambda*(epsilon11+epsilon22+epsilon33)');
eq2=sym('sigma22=2*G*epsilon22+lambda*(epsilon11+epsilon22+epsilon33)');
eq3=sym('epsilon33=-v*(sigma11+sigma22)/E');

[sigma11,sigma22,epsilon33]=solve(eq1,eq2,eq3);
sigma11=vpa(sigma11,8);
sigma22=vpa(sigma22,8);
epsilon33=vpa(epsilon33,8);

程序如上，需要的答案sigma11, sigma22, epsilon33都是1x1 sys类型，没有具体数字，请问怎么解决？

修改如下：
clear all; clc

E=2*10^5;
v=0.3;
G=E/(2*(1+v));
lambda=(v*E)/((1+v)*(1-2*v));
epsilon11=1.7833*10^-3;
epsilon22=1.6*10^-3;
syms sigma11 sigma22 epsilon33;

eq1= sigma11==2*G*epsilon11+lambda*(epsilon11+epsilon22+epsilon33);
eq2= sigma22==2*G*epsilon22+lambda*(epsilon11+epsilon22+epsilon33);
eq3= epsilon33==-v*(sigma11+sigma22)/E;

[sigma11,sigma22,epsilon33]=solve(eq1,eq2,eq3);
sigma11=vpa(sigma11,8);
sigma22=vpa(sigma22,8);
epsilon33=vpa(epsilon33,8);

val_sigma11 = double(sigma11)
val_sigma22 = double(sigma22)
val_epsilon33 = double(epsilon33)

matlab2013b下运行通过，版本太低了别怪别人。
val_sigma11 =

-0.0014

val_sigma22 =

497.4286

val_epsilon33 =

469.2286

syms a b c e2 e3 e4; i=a^2/2+6/5*a*b+4/3*a*c+3/4*b^2+12/7*b*c+c^2-(e2*a+e3*b+e4*c); x=diff(i,a);y=diff(i,b);z=diff(i,c); s=solve(x,y,z,a,b,c); a = s.a b = s.b c = s.ca =  210*e4+225*e2-420*e3  b =  -420*e4-420*e2+2450/3*e3  c =  441/2*e4+210*e2-420*e3

解方程组失效，可将程序改为： clear E=2*10^5; v=0.3; G=E/(2*(1+v)); lambda=(v*E)/((1+v)*(1-2*v)); epsilon11=1.7833*10^-3; epsilon22=1.6*10^-3; epsilon33=-2*v*(G+lambda)*(sigma11+sigma22)/(2*v+E) sigma11=2*G*epsilon11+lambda*(epsilon11+epsilon22+epsilon33) sigma22=2*G*epsilon22+lambda*(epsilon11+epsilon22+epsilon33) 最后运行结果是： >> epsilon33=-2*v*(G+lambda)*(epsilon11+epsilon22)/(2*v+E) epsilon33 = -0.0020 >> sigma11=2*G*epsilon11+lambda*(epsilon11+epsilon22+epsilon33) sigma11 = 439.5156 >> sigma22=2*G*epsilon22+lambda*(epsilon11+epsilon22+epsilon33) sigma22 = 411.3156