[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： &g}P)xr  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); AP z"k?D0  
net.trainParam.show = 50; l4mRNYv)z  
net.trainParam.lr = 0.05; v`L]dY4,  
net.trainParam.epochs = 300; C@;e
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net.trainParam.goal = 1e-5; IAbQgBvUD  
p = [-1 -1 2 2;0 5 0 5]; zT}vaU6  
t = [-1 -1 1 1]; R68:=E4  
net=train(net,p,t); }.s%J\ckx  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 K:9AP{+  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 ]Vj($O:  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 An}RD73!w  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 ;jx[ +  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 |) cJ  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 yQ^,>eh  
TRAINGD, Performance goal met. |3FGMg%  
a = sim(net,p) Q
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plot(p,t,p,a,'o') P3!@}!r8  
但是为什么老是报错： CN` ~DD{  
??? Input argument "net" is undefined. 9:g]DIL