function visualizeFit(X, mu, sigma2)
[X1,X2] = meshgrid(0:.5:35);
Z = multivariateGaussian([X1(:) X2(:)],mu,sigma2);
Z = reshape(Z,size(X1));
plot(X(:, 1), X(:, 2),'bx');
hold on;
if (sum(isinf(Z)) == 0)
contour(X1, X2, Z, 10.^(-20:3:0)');
end
hold off;
end