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Old 09-02-2012, 01:01 AM
Andrs Andrs is offline
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Join Date: Jul 2012
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Default 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
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