[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： wP-BaB$_  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); hf#[Vns  
net.trainParam.show = 50; U42B(ow  
net.trainParam.lr = 0.05; %#gHa  
net.trainParam.epochs = 300; En&`m  
net.trainParam.goal = 1e-5; N5m+r.<;  
p = [-1 -1 2 2;0 5 0 5]; gxa@da  
t = [-1 -1 1 1]; vfnVN@ 5  
net=train(net,p,t); FH Hi/yh  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 BBkYc:B=SA  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 #21t8  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 #0*OkZMt  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 bIs@CDB  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 LS(J%\hMDm  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 h4N%(?7  
TRAINGD, Performance goal met. 0J \hku\  
a = sim(net,p) w]-,X`  
plot(p,t,p,a,'o') hlIh(\JZ4s  
但是为什么老是报错： IgxZ_2hO  
??? Input argument "net" is undefined. -XcX1_