##  [Functional Derivative](/functional-derivative) 

  ##  [Functional Derivative](https://natural.quantumdictionary.io/functional-derivative-0) 

  

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**Natural & Formal Sciences Dictionary**

 







 

 

 

 



 

 

 

 

Definition

The linear operator that gives the first-order change in a scalar-valued functional induced by an infinitesimal perturbation of its input function; it generalizes the notion of ordinary derivative to maps from function spaces to scalars.