MATLAB: Neural network nprtool tansig vs logsig

Question

Hello,

I am a little confused about the nprtool in the neural network toolbox. It generates a two layer feedforward network with a tansig activation on the output layer. However it expects a binary output with {0,1} and it seems to work right.

I wonder why doesn't it use logsig activation if the output will be {0,1}. When I manually modify the output activation to logsig the generated output gets compressed to [0.5,1] range, which is wrong.

I can't explain what seems to be the problem.

Thanks

Answer 1

Most of the nets have a default mapminmax processing default that transforms outputs to the range (-1,1). For that range tansig is appropriate. There also is a default reverse transformation that yields the original target range.

My guess is that when you imposed 'logsig' the processing got screwed up.

Exactly what commands did you use to switch to 'logsig'?

Hope this helps.

*Thank you for formally accepting my answer.

Greg