How to extract feature from autoencode​r/stackaut​oencoder ?

Suppose, 2 autoencoder is stacked together and a softmax layer is used for classification.

At the time of fine tuning %deepnet = stack(autoenc1,autoenc2,softnet); [deepnet,tr]=train(deepnet,X,T);% are used.

After finetuning, i need feature from 'autoenc1'' or 'autoenc2'.

How can i extract the feature?

[Hajar Ahmadieh]

by activations() function

[Mandar Kale]

Hajar Ahmadieh , can you pleasee post a demo code for it THi would be a great help