Body: <p>I've read in this: F. Rosenblatt, <em>Principles of neurodynamics. perceptrons and the theory of brain mechanisms</em> that in the Multilayer Perceptron the activation functions in the second, third, ..., are all non linear, and they all can be different. And in the first layer, they are all linear.</p>
  <p>Why?</p>
  <p>On what does this depends?</p>
  <ol start="2">
  <li>When it is said &quot;the neural network learns automatically&quot;, in colloquial words, what does it mean?</li>
  </ol>
  <p>AFAIK, one first train the NN, then at some point NN learns. When does the &quot;automatically&quot; enters then?</p>
  <p>Thanks in advance for your help.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-22T01:03:00.100Z
Comments.Text: Hello Veronica. Could you please focus on 1 question at a time (so that people can focus on 1 problem at a time)? So, I would suggest that you remove the second question and ask it in a different/separate post. Please, try also to put your **specific** question in title to give immediately the idea of what your post is about to the readers.
Comments.UserDisplayName: nbro
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-22T16:00:56.930Z
Comments.Text: @nbro Hello moderator nbro. Ok, but notice that nxglogic has answered both questions, if I edit my question, that would affect their answer, so?. I've modified the title to make it more specific.
Comments.UserDisplayName: Verónica Rmz.
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-25T01:20:42.257Z
Comments.Text: Helpful -> https://ai.stackexchange.com/questions/7088/how-to-choose-an-activation-function and their respective answers.
Comments.UserDisplayName: Verónica Rmz.
Tags: <neural-networks><activation-functions><feedforward-neural-networks><multilayer-perceptrons>
Title: About the choice of the activation functions in the Multilayer Perceptron, and on what does this depends?
UserDisplayName: Verónica Rmz.
ThreadText: # About the choice of the activation functions in the Multilayer Perceptron, and on what does this depends?
  
  (Asked by: username_0 on 2021-04-21)
  
  I've read in this: F. Rosenblatt, *Principles of neurodynamics. perceptrons and the theory of brain mechanisms* that in the Multilayer Perceptron the activation functions in the second, third, ..., are all non linear, and they all can be different. And in the first layer, they are all linear.
  
  Why?
  
  On what does this depends?
  
  2. When it is said "the neural network learns automatically", in colloquial words, what does it mean?
  
  AFAIK, one first train the NN, then at some point NN learns. When does the "automatically" enters then?
  
  Thanks in advance for your help.
  
  **Tags:** neural-networks, activation-functions, feedforward-neural-networks, multilayer-perceptrons
  > **Comments:**
  > **username_1**: Hello Veronica. Could you please focus on 1 question at a time (so that people can focus on 1 problem at a time)? So, I would suggest that you remove the second question and ask it in a different/separate post. Please, try also to put your **specific** question in title to give immediately the idea of what your post is about to the readers.  
  > **username_0**: @nbro Hello moderator nbro. Ok, but notice that nxglogic has answered both questions, if I edit my question, that would affect their answer, so?. I've modified the title to make it more specific.  
  > **username_0**: Helpful -> https://ai.stackexchange.com/questions/7088/how-to-choose-an-activation-function and their respective answers.  
  
  ---
  
  ## 0 answers
  
  