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JmySVMLearner C parameter question
niccolo_camarli
Member Posts: 3 
Contributor I
Dear all,
I'm trying to use JmySVMLearner, but i have question that i'm not able to answer by myself.
One of the parameters of this operator is C, what happens if i select a C value= 0.0 ?does the algorithm switch to the linear separable case of the SVM (no constraint for the Langrange Multipliers) ?
Tank You in advance for your help
I'm trying to use JmySVMLearner, but i have question that i'm not able to answer by myself.
One of the parameters of this operator is C, what happens if i select a C value= 0.0 ?does the algorithm switch to the linear separable case of the SVM (no constraint for the Langrange Multipliers) ?
Tank You in advance for your help
0
Answers
see the mySVM documentation:
C: the SVM complexity constant. If not set, 1/avg(K(x,x)) is used.
Here, 0 means "not set" :-)
If you set the log level in the process root operator low enough, the SVM will log the value that is actually used.
Cheers,
Simon
But where this 1/avg(K(x,x)) comes from?
I found this value also on the website of Stefan Rüping (Mysvm ) and also on SVMlight website, could you give me some reference that explains the reason of this C guess?
Tank You
have a look at the references below. Thinking about it, it occurs to me that the formula I copied from the mySVM documentation may be wrong. Please have a look at the literature to be sure.
Cheers,
Simon
http://www-stat.stanford.edu/~tibs/ElemStatLearn/
Hastie, T., Rosset, S., Tibshirani, R. and Zhu, J. (2004). The entire regularization
path for the support vector machine, Journal of Machine
Learning Research 5: 1391-1415.