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Gaussian combination kernel ,Sigma1,Sigma2,Sigma3 meanings.

hosam37rhosam37r Member Posts: 1 Learner II
edited November 2018 in Help

Hello

I'm trying to use SVM with Gaussian combination kernel.

However i need to enter the paramters Sigma1,Sigma2,Sigma3.

In order to pick  suitable values.Does anybody have more information about the mathmetical model and the meaning of these parameters?

Thanks

Answers

  • MartinLiebigMartinLiebig Administrator, Moderator, Employee, RapidMiner Certified Analyst, RapidMiner Certified Expert, University Professor Posts: 3,528 RM Data Scientist

    Hi Hosam,

     

    sure :) Have a look at /

    com.rapidminer.operator.learner.functions.kernel.jmysvm.kernel;

    in our source code on https://github.com/rapidminer/rapidminer-studio .

    The definition is:

     

    	public double calculate_K(int[] x_index, double[] x_att, int[] y_index, double[] y_att) {
    		double norm2 = norm2(x_index, x_att, y_index, y_att);
    		double exp1 = sigma1 == 0.0d ? 0.0d : Math.exp((-1) * norm2 / sigma1);
    		double exp2 = sigma2 == 0.0d ? 0.0d : Math.exp((-1) * norm2 / sigma2);
    		double exp3 = sigma3 == 0.0d ? 0.0d : Math.exp((-1) * norm2 / sigma3);
    		return exp1 + exp2 - exp3;
    	}

    Where norm2 is: ||x-y||^2

     

    Best,

    Martin

     

    - Sr. Director Data Solutions, Altair RapidMiner -
    Dortmund, Germany
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