perform command in neural netwrok

I cant understand how perform function works in neural network! at the end of this page in section 5: https://www.mathworks.com/help/nnet/gs/classify-patterns-with-a-neural-network.html?requestedDomain=www.mathworks.com the performance is calculated but without any explanation! what does it mean? is it a good network? In other examples the performance value is 19! which one is better?

[Greg Heath]

Ahhh. An ally in dismay !

https://www.mathworks.com/matlabcentral/newsreader/view_thread/349050#955175

Searching the NEWSGROUP using the search word 'QUICKIE' find

http://www.mathworks.com/matlabcentral/newsreader/view_thread/348883#955252.

Compare those results with perform.

Hope this helps.

Greg

Answer 1

[Greg Heath]

 help perform
 doc perform
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    net        = patternnet;
   performFcn = net.performFcn

% performFcn = 'crossentropy' AHA!

 help crossentropy
 doc crossentropy

% Still isn't clear? ... Join the club. I used to know what crossentropy was. However, when I gave technical talks (I'm an engineer, not a physicist) no one else knew or cared. What they wanted was error rates and Rsquare.

My preferences are

 NORMALIZED MEAN SQUARE ERROR NMSE = 1-Rsquare %[ 0,1]

and

 PER CENT ERROR RATE % [ 0, 100]

See my QUICKIES post

Hope this helps.

Thank you for formally accepting my answer

Greg

PS If you are a glutten for punishment, see GOOGLE

greg MATLAB crossentropy  ==> 39,500 hits  (;>)

otherwise see

                               HITS
                      NEWSGROUP    ANSWERS

crossentropy 28 62

crossentropy greg 6 46

Hope this helps.

Thank you for formally accepting my answer

Greg