bpnn1.m

bp经典测试源码

function main()
SamNum=100;
TestSamNum=101;
HiddenUnitNum=10;
InDim=1;
OutDim=1;
rand('state',sum(100*clock))
NoiseVar=0.1;
Noise=NoiseVar*randn(1,SamNum);
SamIn=8*rand(1,SamNum)-4;
SamOutNoNoise=1.1*(1-SamIn+2*SamIn.^2).*exp(-SamIn.^2/2);
SamOut=SamOutNoNoise+Noise;

TestSamIn=-4:0.08:4;
TestSamOut=1.1*(1-TestSamIn+2*TestSamIn.^2).*exp(-TestSamIn.^2/2);

figure
hold on
grid
plot(TestSamIn,TestSamOut,'k--')
xlabel('Input x')
ylabel('Output y')

MaxEpochs=2000;
lr=0.005;
Eo=0.5;

W1=0.2*rand(HiddenUnitNum,1)-0.1;
B1=0.2*rand(HiddenUnitNum,1)-0.1;
W2=0.2*rand(OutDim,HiddenUnitNum)-0.1;
B2=0.2*rand(OutDim,1)-0.1;

W1Ex=[W1 B1];
W2Ex=[W2 B2];
 
SamInEx=[SamIn' ones(SamNum,1)]';
ErrHistory=[];
for i=1:MaxEpochs

HiddenOut=logsig(W1Ex*SamInEx); %正向传播的输出
HiddenOutEx=[HiddenOut' ones(SamNum,1)]';
NetworkOut=W2Ex*HiddenOutEx;

Error=SamOut-NetworkOut;
SSE=sumsqr(Error)

ErrHistory=[ErrHistory SSE];  %记录权值调整后的误差
if SSE<Eo,break, end
 

Delta2=Error;%计算反向传播误差
Delta1=W2'*Delta2.*HiddenOut.*(1-HiddenOut);

dW2Ex=Delta2*HiddenOutEx';%计算权值调节量
dW1Ex=Delta1*SamInEx';

W1Ex=W1Ex+lr*dW1Ex;%权值调节
W2Ex=W2Ex+lr*dW2Ex;

W2=W2Ex(:,1:HiddenUnitNum);
end

i
W1=W1Ex(:,1:InDim)
B1=W1Ex(:,InDim+1)
W2
B2=W2Ex(:,1+HiddenUnitNum)


TestHiddenOut=logsig(W1*TestSamIn+repmat(B1,1,TestSamNum));%测试
TestNNOut=W2*TestHiddenOut+repmat(B2,1,TestSamNum);
plot(TestSamIn,TestNNOut,'k*')

figure
hold on
grid
[xx,Num]=size(ErrHistory);
plot(1:Num,ErrHistory,'k-');