Uniform pdf from difference of two stochastic variables?

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Discussion Overview

The discussion revolves around the quest to identify a probability distribution (D) such that the difference between two independent stochastic variables, X1 and X2, drawn from this distribution results in a uniform distribution on the interval [0,1]. Participants explore the feasibility of such a distribution and share their attempts and challenges in deriving it.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about whether a distribution with the desired property exists.
  • Another participant suggests a method involving a uniform distribution on the interval (-1/2, 1/2) and proposes using the characteristic function to derive the necessary distribution.
  • A different participant mentions difficulties in calculating the inverse Fourier transform needed for the proposed method, indicating that both analytical and numerical attempts in Mathematica were unsuccessful.
  • One participant speculates that there may not be a density function for the distribution and suggests exploring the distribution function instead, providing a related integral expression.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of the desired distribution. There are multiple competing views regarding the methods to explore, and uncertainty remains about the feasibility of achieving a uniform distribution from the difference of two stochastic variables.

Contextual Notes

Participants highlight challenges related to the calculation of the inverse Fourier transform and the potential absence of a density function, indicating limitations in their approaches and the need for further exploration.

bemortu
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Hi,

I'm trying to find a probability distribution (D) with the following property:
Given two independent stochastic variables X1 and X2 from the distribution D, I want the difference Y=X1-X2 to have a uniform distribution (one the interval [0,1], say).

I don't seem to be able to solve it. I'm not even sure that such a distribution exists...

Any ideas?
 
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Sugestion (outline). For simplicity I will make it uniform on the interval (-1/2,1/2). The characteristic function is sin(t/2)/(t/2). Take the square root and then the inverse Fourier transform should give you something close to what you want (the sum of two random variables will have a uniform distribution).
 
Yes, that's one of the things I already tried. The problem is that I didn't manage to calculate that inverse Fourier transform. I tried it with Mathematica, which could not find an analytical solution. I also tried the numerical inverse Fourier transform in Mathematica but it also failed. Maybe it means that this distribution doesn't exist?
 
My guess: there is no density function. You might try getting the distribution function.

F(y) - F(x) = 1/2π ∫{(exp(ity) - exp(itx))φ(t)/(it)}dt
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http://mathforum.org/kb/forumcategory.jspa?categoryID=16

You might try the above forum - it is more mathematical.
 
Last edited:

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