[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： 4}
b:..Ku  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); F.w#AV  
net.trainParam.show = 50; @uWD>(D  
net.trainParam.lr = 0.05; iTyApLV  
net.trainParam.epochs = 300; P,], N)  
net.trainParam.goal = 1e-5; lKSI5d  
p = [-1 -1 2 2;0 5 0 5]; /qY(uPJ  
t = [-1 -1 1 1]; ;]e"bX  
net=train(net,p,t); mQ)l`
wGh  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 "@Fxfd+Ot  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 %iML??S  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 kF7Al]IgT  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 ,4UJ|D=J  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 79fg%cSb  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 nhxl#  
TRAINGD, Performance goal met. 6<GWDO  
a = sim(net,p) J)+eEmrU  
plot(p,t,p,a,'o') r-uIFhV^  
但是为什么老是报错： 
M>#S z  
??? Input argument "net" is undefined. r +fzmb