Default Kernel

function [ result ] = defaultKernel(x, y, A)
%One of many kernel functions.  Takes vectors x and y, returns kernel
%function as a dot product using a positive definite matrix A
[xm xn] = size(x);
[ym yn] = size(y);
[R isPosDef] = chol(A);
if isPosDef ~= 0 || xm ~= ym || xn ~= yn || xn == 1
    disp('sorry, this function is idiot proof.  Please enter in a positive definite matrix A');
    result = -1;
    return;
end

result = x * (A * y');