#1




meaning of gamma in polynomial kernel
In libsvm the polynomial kernel is defined in the following way:
(gamma*u'*v + coef0)^degree). What is the meaning of gamma in the poly kernel? In our exercise the polynomial kernel only contains the parameters coef0 and degree (and C). There is no reference to a gamma parameter. I have guessed the value 1 to gamma (no effect when multiplying the inner product) but I am not sure because its purpose is not clear for me in the poly case. If we do not assign any values, the default value given by libsvm is 1/# features. In our case,it will be 1/2. Any clarifications about this gamma in poly is appreciated 
#2




Re: meaning of gamma in polynomial kernel
See slide 6 of lecture 15, and the discussion starting about 21 minutes into the lecture.

#3




Re: meaning of gamma in polynomial kernel
Quote:
Edit: I wrote this before I saw the above reply.
__________________
Where everyone thinks alike, no one thinks very much 
#4




Re: meaning of gamma in polynomial kernel
Thanks for the quick reply!..may be i should have been more alert

#5




Re: meaning of gamma in polynomial kernel
A simple way to view is that it is as if you have scaled all your down by before applying the no polynomial kernel. Hope this helps.
__________________
When one teaches, two learn. 
#6




Re: meaning of gamma in polynomial kernel
Thanks for the explanation!

Tags 
libsvm, polynomial 
Thread Tools  
Display Modes  

