Directional Derivative

Directional Derivative : Derivative of a function along any given specific direction

represents a surface. Directional Derivative of along the direction of vector is dot product of with unit vector along

Significance of Directional Derivative:

In the following activity you can change the function to find directional derivative at the point input and along the vector . gives direction of maximum change. Significance of Directional Derivative (): if there is a very small change in the input along the direction of vector , then corresponding change in the output will be times the evaluated at