[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： HqZ3]  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); {cW%i:  
net.trainParam.show = 50; -/7[\S  
net.trainParam.lr = 0.05; :B(vk3;U!  
net.trainParam.epochs = 300; ISbhC!59  
net.trainParam.goal = 1e-5; t}!Y}D  
p = [-1 -1 2 2;0 5 0 5]; X<j(AAHE  
t = [-1 -1 1 1]; Ul/Uk n$  
net=train(net,p,t); v'vYNh  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 D=0^"7K  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 ;ye5HlH}.  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 y>5??q  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 ^`MGlI}  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 9CxFj)#5F  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 whoQA}X>  
TRAINGD, Performance goal met. }%@q; "9`  
a = sim(net,p) gZ^'hW-{  
plot(p,t,p,a,'o')  s_p\ bl.  
但是为什么老是报错： h3<L,Olp  
??? Input argument "net" is undefined. V=?qU&r<+