Derivative of Stochastic Function

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Discussion Overview

The discussion revolves around the differentiation of stochastic functions, specifically addressing the question of how to calculate the derivative of a stochastic function, denoted as \(\frac{d\xi}{dt}\), where \(\xi(t)\) is a random function with a known distribution, such as Gaussian. The scope includes theoretical considerations regarding stochastic calculus and the properties of derivatives in the context of randomness.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions whether it is possible to calculate \(\frac{d\xi}{dt}\) for a stochastic function.
  • Another participant asserts that a derivative cannot be defined for stochastic functions due to their discontinuous nature, suggesting that the derivative's definition relies on the behavior of differences as they approach zero.
  • A subsequent post reiterates the inquiry about how to compute \(\frac{d\xi}{dt}\), indicating a desire for clarification or alternative methods.
  • Another response states that there is no preferable method to calculate \(\frac{df}{dt}\) in the context of stochastic functions.

Areas of Agreement / Disagreement

Participants express disagreement regarding the possibility of calculating the derivative of a stochastic function, with some asserting it is not feasible while others seek clarification on potential methods.

Contextual Notes

The discussion highlights limitations in defining derivatives for stochastic functions, particularly concerning the continuity and behavior of such functions as they approach specific values.

Apteronotus
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Hi,

A quick question regarding random functions.
Suppose [tex]\xi(t)[/tex] is a stochastic function. In other words, its value at time t is random with some known distribution (Gaussian, say).
Is there any way of calculating [tex]\frac{d\xi}{dt}[/tex]?

Thanks,
 
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No, there is not. A derivative should not depend on the way of tending the difference df to zero if dt is small. In case of a stochastic (=discontinuous) function it is not the case.
 
Last edited:
So how can we calculate [tex]\frac{d\xi}{dt}[/tex]?
 
There is no a preferable way to calculate df/dt in your case.
 

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