Gaussian combination kernel ,Sigma1,Sigma2,Sigma3 meanings.

hosam37r

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

MartinLiebig

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