---
tag: 0B6QWX3086
kind: concept
name: Strict differentiability
aliases: [strictly-differentiable]
msc: [26B05]
uses: [06EH97V2A7]
sources:
  - url: https://en.wikipedia.org/wiki/Strict_differentiability
    locator: Basic definition
same_as:
  wikidata: Q7623614
  wikipedia: Strict differentiability
---

## Summary

A function is strictly differentiable at a point when a single linear map approximates all its difference quotients near that point. Both points of each quotient can move.
This is stronger than the [[Fréchet derivative|06EH97V2A7]] condition, in which one of the two points stays fixed.