[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： $Q/@5f'T`9  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); B-MS@<2  
net.trainParam.show = 50; {$z54nvw$  
net.trainParam.lr = 0.05; PY5&Fwjc  
net.trainParam.epochs = 300; !i;6!w  
net.trainParam.goal = 1e-5; m !*F5x  
p = [-1 -1 2 2;0 5 0 5]; SUc%dpXZa  
t = [-1 -1 1 1]; <Q
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net=train(net,p,t); rtuaU=U  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 ]%E
h"   
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 =~+ WJN  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 D5lQ0_IeW  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 irAXXg  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 ,W}:vdC  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 \jiE:Qt  
TRAINGD, Performance goal met. Y"mFUW4  
a = sim(net,p) efXnF*Z  
plot(p,t,p,a,'o') L]kBY2c  
但是为什么老是报错： *D?_,s  
??? Input argument "net" is undefined. ^O_Z5NbC3