AI engineering glossary · Calculus optimisation
What is directional derivative?
Directional derivative: The rate at which a function changes when you move from a point in a chosen direction. It equals the dot product of the gradient with a unit vector in that direction, and it is largest when that direction matches the gradient.
Directional derivative: an example
For f(x, y) = x^2 + y^2 at (3, 4), moving along the unit vector (1, 0) gives 6 * 1 + 8 * 0 = 6 per unit step.
Related terms
More Calculus optimisation terms
- Duality
- Euler's number
- Exponential function
- Feasible region
- Finite difference
- First-order condition
- Flat minimum
- Forward-mode automatic differentiation
Where you learn it
Directional derivative is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.