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：
8 C# S- W4 R5 @. P7 C( gnet=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd');

8 @) l6 b6 p& w- g6 {7 ^, c' b
# K( f2 E$ ?1 m5 Enet.trainParam.show = 50;
net.trainParam.lr = 0.05;
& S# M8 I0 {& h' w9 L1 L, b* B  [net.trainParam.epochs = 300;
net.trainParam.goal = 1e-5;
1 H2 \+ D/ D! x& W0 O& X$ U' F5 E, kp = [-1 -1 2 2;0 5 0 5];
2 p% H7 }7 p) V' ]6 d7 pt = [-1 -1 1 1];
; W: `" G- I$ g( K0 x

net=train(net,p,t);
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10


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
' N- z: y* {2 z: ~' zTRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10
$ g' r4 _* H7 t2 y) jTRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10
0 t) ^9 K: ^2 S) i7 y; z, JTRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10
TRAINGD, Performance goal met.
$ i5 v; t( L$ Z. d# A: L* d3 ea = sim(net,p)


plot(p,t,p,a,'o')
3 j) l: f8 C+ s$ F

. P* e0 G. K. M# p8 ]- }* G" X0 [% [但是为什么老是报错：
??? Input argument "net" is undefined.