Neural Network Output :Scaling the output range.
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Hi,
The output layer of my neural network (3 layered) is using sigmoid as activation which outputs only in range [0-1]. However, if I want to train it for outputs that are beyond [0-1], say in thousands, what should I do?
For example if I want to train
input ----> output
0 0 ------> 0
0 1 ------> 1000
1000 1 ----> 1
1 1 -------> 0
My program works for AND, OR, XOR etc. As input output are all in binary.
There were some suggestion to use,
Activation:
-----------
y = lambda*(abs(x)*1/(1+exp(-1*(x))))
Derivative of activation:
-------------------------
lambda*(abs(y)*y*(1-y))
This did not converge for the mentioned training pattern. Are there any suggestion please?
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채택된 답변
Greg Heath
2012년 1월 31일
Hello Greg,
Thanks again for answering the question. For my case, no rigid bound,
1. INCORRECT. ALL 3 VARIABLES ARE BOUNDED:
0 <= X1, Y <= 1000
0<= X2 <= 1.
2. HOWEVER, SINCE THE INPUT SCALES ARE DIFFERENT BY A FACTOR OF THOUSAND, X1 AND Y SHOULD BE TRANSFORMED BY VIA LOGS AND/OR POWERS. E.G.,
X1n = LOG10( 1 + X1 ) / LOG10( 1001 ) ==> 0 <= X1n <= 1
SIMILARLY FOR Y
HOPE THIS HELPS.
GREG
추가 답변 (1개)
Greg Heath
2012년 1월 29일
If the target has rigid bounds, scale the data to either [0,1] or [-1,1] and use either LOGSIG or TANSIG, respectively.
Otherwise, standardize to zero-mean/unit variance and use PURELIN.
To recover the original data scale, just use the reverse tranformations.
Hope this helps.
Greg
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