[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： z>|)ieL  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); Ra0=q4vdk  
net.trainParam.show = 50; ?ql2wWsQO  
net.trainParam.lr = 0.05; QF.3c6O@  
net.trainParam.epochs = 300; D M}s0O$0  
net.trainParam.goal = 1e-5; JR)/c6
j  
p = [-1 -1 2 2;0 5 0 5]; 7 5|pp  
t = [-1 -1 1 1]; 7WP%J-   
net=train(net,p,t); E+z18Lf?  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 F@1d%c  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 V!xwb:J  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 *> KHRR<N  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 \B&6TeR  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 \yG`Sfu2  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 (f~gEKcB2u  
TRAINGD, Performance goal met. /W`$yM3  
a = sim(net,p) sMm/4AY]  
plot(p,t,p,a,'o') \vVSh  
但是为什么老是报错： }
/p/pVz  
??? Input argument "net" is undefined. b_=8!Q.: