新手求助~（关于初级的神经网络问题）

Continue

各位大虾，我在网上看到的教程里的一个程序段，本来想要试试看的：
$ q$ K2 T! j8 Z7 ~8 Y0 Vnet=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd');

& `/ B3 q- i. O+ A$ P
net.trainParam.show = 50;
9 Y1 p$ T+ }. q' f) ^+ ynet.trainParam.lr = 0.05;
net.trainParam.epochs = 300;
net.trainParam.goal = 1e-5;
* _# B& B( s3 G' v3 t: O! sp = [-1 -1 2 2;0 5 0 5];
t = [-1 -1 1 1];

- R+ Z: Z+ v7 \) j4 ]6 `
2 l% Q8 f& j' e5 @* @* L; Wnet=train(net,p,t);
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10
4 J0 D5 b6 c' ~0 _4 m( a$ A
4 [* l! k: ~$ Y+ J8 H- r" @
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10
- P9 }. x4 _4 S* s- nTRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10
) G% X- @$ B# t9 |# ITRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10
TRAINGD, Performance goal met.
a = sim(net,p)


plot(p,t,p,a,'o')


, M9 m, s+ }, G; ]+ p% W但是为什么老是报错：
0 f, {3 s# \  A2 Z: c* \??? Input argument "net" is undefined.