Question

When a function has directional derivative in all direction?

Answer 1

Answer:

For a function of two variables at a point.

Step-by-step explanation:

It is possible to have a function of two variables and a point in the domain of such that has a directional derivative in every direction at , but is not differentiable at , i.e., the gradient vector of at does not exist.

Answer 2

For a function of two variables at a point. It is possible to have a function of two variables and a point in the domain of such that has a directional derivative in every direction at , but is not differentiable at , i.e., the gradient vector of at does not exist

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