[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： ~f>2U]F>5  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); wTq{sW&  
net.trainParam.show = 50; }^ FulsC  
net.trainParam.lr = 0.05; Rd&9E  
net.trainParam.epochs = 300; pHE}ytcT  
net.trainParam.goal = 1e-5; PO-"M)M  
p = [-1 -1 2 2;0 5 0 5]; s}5+3f$f  
t = [-1 -1 1 1]; _'0 @%P%
 
net=train(net,p,t); &m^@9E)S/  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 /8ynvhF#  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 @'FE2^~Jj  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 ^z;JVrW  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 "E*e2W  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 )q~DT
R^z-  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 Kyg=$^{>G  
TRAINGD, Performance goal met. vv0Q$ O->  
a = sim(net,p) X$?3U!  
plot(p,t,p,a,'o') @\P4/+"9  
但是为什么老是报错： ^V*-1r1  
??? Input argument "net" is undefined. BzJ;%ywS