Directional Derivative

This applet illustrates the concept of directional derivative.
  1. Set the coordinates of point with the X and Y sliders.
  2. Set the direction of the unit vector with the Angle slider.
  3. Observe the curve that results from the intersection of the surface of the function with the vertical plane corresponding to .
  4. The directional derivative of the function at the point along the direction of the vector is the slope of the tangent line to the previous curve at .
Change the function and repeat the previous steps.
Get more info about directional derivatives at http://aprendeconalf.es.