# Directional Derivative

> Source: https://sukruyusufkaya.com/en/glossary/yonlu-turev
> Updated: 2026-05-13T21:00:55.161Z
> Type: glossary
> Category: matematik-istatistik-optimizasyon
**TLDR:** A derivative concept that measures how fast a function changes in a specific direction.

<p>The directional derivative studies not just the overall change of a function, but its change along a chosen direction. This is useful even when the gradient gives the direction of maximum increase, because it lets us evaluate the effect of a specific direction of interest. It has important applications in optimization, geometry, and multivariable analysis. Especially on complex surfaces, it helps us understand how sensitive the system is in selected directions. In that sense, the directional derivative is a tool for examining change in a more targeted and local way.</p>