Partial Derivatives

[monomocoso]

Give an example of a continuous function from \(\displaystyle R^2\) having partial derivatives at (0,0) with \(\displaystyle f_1 (0,0) \neq 0\) and \(\displaystyle f_2 (0,0) \neq 0\) but the vector \(\displaystyle (f_1 (0,0) , f_2 (0,0))\)does not point in the direction of maximal change, even though there is such a direction.