MatLab中如何mapFeature，即：将少数的特征扩展出众多的高次项特征。

mapFeature.m

function out = mapFeature(X1, X2)


degree = 6;
out = ones(size(X1(:,1)));
for i = 1:degree
    for j = 0:i
        out(:, end+1) = (X1.^(i-j)).*(X2.^j);
    end
end

end