zzh911 发表于 2008-9-21 00:17

请教BP神经网络中出现的一个问题

编写的具体程序如下:
>> P=[0.936694,0.981744,1,0.667698,0.830719;
0.664891,0.981744,0.989899,0.667698,0.498492;
0.731759,0.975711,0.979798,0.600792,0.556788;
0.533898,0.975711,0.888889,0.600793,0.600218;
0.246123,0.496107,0.424242,0.424534,0.120379;
0.135998,0.496107,0.525253,0.424534,0.243802;
0.334354,0.049286,0.606061,0.086876,0.210937;
0.141461,0.645391,0.444444,0.632913,0.171543;
0.525646,0.645391,0.919192,0.632912,0.526012;
0.167553,0.022205,0.737374,0.009141,0.019267;
0.326964,0.022205,0.333333,0.009141,0.147202;
0.241284,0.325522,0.919192,0.619236,0.256637;   
0.441056,0.325522,0.989899,0.619236,0.170411]';

T=';

PR=;

net=newff(PR,,{'tansig','purelin'},'trainlm');
net.trainParam.epochs=200;
net.trainParam.goal=0.001;
net=init(net);
net=train(net,P,T);

结果出现
TRAINLM-calcjx, Epoch 0/200, MSE 1.97782e+007/0.001, Gradient 21488.9/1e-010
TRAINLM-calcjx, Epoch 10/200, MSE 493351/0.001, Gradient 2.7615e-010/1e-010
TRAINLM, Maximum MU reached, performance goal was not met.
请问该如何解决,谢谢了,十万火急啊。

frogfish 发表于 2008-9-21 07:29

检查一下你的样本是否有问题,如果样本没有问题可以通过设置 net.trainParam.mu 来调节参数。

net.trainParam.mu 0.001          Initial Mu
net.trainParam.mu_dec 0.1      Mu decrease factor
net.trainParam.mu_inc 10      Mu increase factor
net.trainParam.mu_max 1e10 Maximum Mu

hlhl 发表于 2008-10-25 22:37

请问楼上的mu是什么参数?是所说的变学习率吗?

F117_ren_0 发表于 2008-10-27 11:25

目标误差没达到,
net.trainParam.epochs=200;
net.trainParam.goal=0.001;
要么把训练次数搞高点,至少3000次,要么就吧目标误差写大点,0.01
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