Quote:
Originally Posted by Anne Paulson
I know what gamma is for the radial kernel, but what does it mean for the polynomial kernel? And what is coef0? The bias? If so, why would the default be 0? Wouldn't you usually want an intercept?

see
http://scikitlearn.org/stable/modul...rnelfunctions
also, from the python docs:

 kernel : string, optional (default='rbf')
 Specifies the kernel type to be used in the algorithm.
 It must be one of 'linear', 'poly', 'rbf', 'sigmoid', 'precomputed' or
 a callable.
 If none is given, 'rbf' will be used. If a callable is given it is
 used to precompute the kernel matrix.

 degree : int, optional (default=3)
 Degree of kernel function.
 It is significant only in 'poly' and 'sigmoid'.

 gamma : float, optional (default=0.0)
 Kernel coefficient for 'rbf' and 'poly'.
 If gamma is 0.0 then 1/n_features will be used instead.

 coef0 : float, optional (default=0.0)
 Independent term in kernel function.
 It is only significant in 'poly' and 'sigmoid'.