[求助]新手求助~（关于初级的神经网络问题） [复制链接]

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： huVw+vAA  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); s8 S[w   
net.trainParam.show = 50; HF>Gf2-C  
net.trainParam.lr = 0.05; "e4;xU-  
net.trainParam.epochs = 300; (T+fO}0  
net.trainParam.goal = 1e-5; ~H"Q5Hr  
p = [-1 -1 2 2;0 5 0 5]; e%.Xya#\  
t = [-1 -1 1 1]; ) inhPd  
net=train(net,p,t); ODa+s>a`^  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 g$
+u;ER5  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 t:y} 7un  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 H6i4>U*  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 xDv5'IGBb  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 el GP2x#:  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 ]gI>ay"\QA  
TRAINGD, Performance goal met. tg%s#lLeH  
a = sim(net,p) 4pNIsjl}  
plot(p,t,p,a,'o') 3>LyEXOW  
但是为什么老是报错： d67Q@')00  
??? Input argument "net" is undefined. k+Ew+j1_