2013-05-21, 12:29 AM
Directional derivative denotes the rate of change of the function value when you take one unit-length step along the "directional" vector in parameter space.
They gave you a vector u in the direction of the vector <0, -2, 2>, u itself is not <0, -2, 2>.
In short:
![[Image: 16NW4.jpeg]](http://i.imm.io/16NW4.jpeg)
They gave you a vector u in the direction of the vector <0, -2, 2>, u itself is not <0, -2, 2>.
In short: