Fitcsvm kernel scale on polynomial

I am looking at how the 'Kernel Scale' parameter changes the output function of your hyperplane when using a polynomial kernel. I know when using the gaussian kernel the kernel scale is just gamma in the kernel (i.e. kernel = gamma*||x-y||^2). However I cannot seem to find an answer for it when it comes to the polynomial kernel. Here were some of my attempts to find how the polynomial kernel is changed, but all did not work:

• (1+scale*xy')^d
• (1+1/scale*xy')^d
• (scale+scale*xy')^d
• (1/scale+1/scale*xy')^d
• (1+1/sqrt(scale)*xy')^d
• scale*(1+xy')^d

All the above were tested by plotting the appropriate hyperplane. Any help is much appreciated.

Answer 1

[Laura White]

For all who might have the same question I found the solution. The kernel scale works for the polynomial in the following way:

(1+1/scale^2*xy')^d

It took a lot of guessing to find this, so I hope it helps someone.

[Jose Luis Villaescusa Nadal]

Can you please share how you obtained the hyperplane function of the polynomial csv?

Thanks a lot!