StanfordMLOctave/machine-learning-ex6/ex6/gaussianKernel.m

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Matlab

function sim = gaussianKernel(x1, x2, sigma)
%RBFKERNEL returns a radial basis function kernel between x1 and x2
% sim = gaussianKernel(x1, x2) returns a gaussian kernel between x1 and x2
% and returns the value in sim
% Ensure that x1 and x2 are column vectors
x1 = x1(:); x2 = x2(:);
% You need to return the following variables correctly.
sim = 0;
% ====================== YOUR CODE HERE ======================
% Instructions: Fill in this function to return the similarity between x1
% and x2 computed using a Gaussian kernel with bandwidth
% sigma
%
%
temp = (x1 - x2).^2;
temp = sum((x1 - x2).^2);
temp = temp * (-1);
temp = temp / (2* (sigma^2));
sim = e^(temp);
% =============================================================
end