[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： u!It';j  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); /=#~8  
net.trainParam.show = 50; l;aO"_E1m  
net.trainParam.lr = 0.05; aDLlL?r3  
net.trainParam.epochs = 300; ,PKUgL}w  
net.trainParam.goal = 1e-5; i"DyXIrk2  
p = [-1 -1 2 2;0 5 0 5]; |vG?H#y  
t = [-1 -1 1 1]; D^];6\=.i  
net=train(net,p,t); E2.!|u2  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 H#nJWe_9A  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 &g*1
If  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 mB bGj3u;  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 J=O_nup6C  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 C4-%|+Q i  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 :Us+u-~  
TRAINGD, Performance goal met. Pum&\.l  
a = sim(net,p) Ts=TaRwWf  
plot(p,t,p,a,'o') fp3`O9+em  
但是为什么老是报错： pOl6x iMx  
??? Input argument "net" is undefined. 7fT_]H8