What is the predict formula for fitrsvm (gaussian kernel) generated model?

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Cecil Scott 2016-5-18

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评论： antlhem 2021-5-29

Using fitrsvm, I have generated a model from X and Y data:

mdl = fitrsvm(X,Y,'Standardize',true,...
         'KernelFunction','gaussian','KernelScale','auto');

Given an input x, the predicted output using Matlab is:

y_expected=predict(mdl,x);

My attempt below at replicating 'predict' function does not yield the correct answer as y and y_expected do not agree.

y=mdl.Bias;
for i=1:length(mdl.Alpha)
    xmxd=x-mdl.SupportVectors(i,:);
    y=y + mdl.Alpha(i)*exp(-xmxd*xmxd'/2/mdl.KernelParameters.Scale);
end
y

What is the underlying formula behind the predict function in this case? I need it to write equivalent java code from parameters in the mdl model.

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sanjeev kumar T M 2018-8-12

Hello, Actually i tried with the predictive formula given above but am not able to get the result what am getting using predict function. if any one help me regarding this please. what formula i have to use because i want to use the model in microcontroller to validate. am using 4 predictors and am using gaussian kernel

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回答（2 个）

the cyclist 2016-5-18

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It looks like all the relevant formulas (and references) are in this documentation page.

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the cyclist 2016-5-19

The best form of thanks is upvoting and/or accepting an answer that you find helpful. This rewards the contributor, and points future users to helpful answers.

antlhem 2021-5-29

Could take a look into my question? https://uk.mathworks.com/matlabcentral/answers/842800-why-matlab-svr-is-not-working-for-exponential-data-and-works-well-with-data-that-fluctuates?s_tid=prof_contriblnk

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sanjeev kumar T M 2018-8-12