Gradient vector of a given scalar field in 2D

Sketching the Gradient vector
Gradient vector of a given scalar field in 2D
Enter an equation of a curve and the gradient vector at the point A on the curve, as (f_x, f_y) evaluated at the point A.   Either drag the point A or animate by clicking on the point A in the left column.

Information: Gradient vector of a given scalar field in 2D