Distribution of sum of two circular uniform RVs in the range [0, 2 pi)

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Discussion Overview

The discussion focuses on deriving the distribution of the sum of two circular uniform random variables (RVs) defined in the range [0, 2π). Participants explore the implications of the modulo operation on the sum and consider variations involving different distributions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks analytical steps for deriving the distribution of the sum of two circular uniform RVs modulo 2π.
  • Another participant suggests a formula for calculating the probability distribution of the sum, indicating that it involves considering the ranges of the sums and applying the modulo operation.
  • A different participant proposes a scenario where one RV is circular uniform and the other is uniform over a different range, questioning whether their sum remains uniform and expressing uncertainty about the resulting range.
  • Concerns are raised about the clarity of whether the sum is to be considered modulo 2π, with references to conflicting definitions of the modulo operation found in external sources.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the treatment of the modulo operation in the context of the sum of the RVs. There is no consensus on whether the sum remains uniform or how the ranges interact.

Contextual Notes

Participants note the ambiguity in definitions of the modulo operation, which may affect the interpretation of results. The discussion also highlights the complexity introduced by varying the distributions of the RVs.

nikozm
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distribution; uniform
Hello,

I would like to know the analytical steps of deriving the distribution of sum of two circular (modulo 2 pi) uniform RVs in the range [0, 2 pi).

Any help would be useful

Thanks in advance!
 
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Easiest way is <br /> P(0 \leq Z = (\Theta + \Phi) \mod 2 \pi &lt; z ) = P(0 \leq \Theta + \Phi &lt; z) + P(2\pi \leq \Theta + \Phi &lt; z + 2\pi)<br /> for z \in [0, 2\pi) and \Theta, \Phi are independent and uniformly distributed on [0, 2\pi).
 
I try to utilize this formula to a similar case, but the result seems too complicated. What if one of two RVs is a circular (mod 2 pi) uniformly distributed in [0, 2 pi) and the other one is an independent uniform RV in the range [-2^(-q) pi, 2^(-q) pi], where q is a nonnegative integer greater or equal than one. I presume that their sum is also a uniform RV, but I am not sure about its range.

Can you help me on this.

Thank you so much in advance.
 
In the original it is not clear to me that the sum is also mod 2pi. If not then the result will be different.

nikozm said:
I try to utilize this formula to a similar case, but the result seems too complicated. What if one of two RVs is a circular (mod 2 pi) uniformly distributed in [0, 2 pi) and the other one is an independent uniform RV in the range [-2^(-q) pi, 2^(-q) pi], where q is a nonnegative integer greater or equal than one. I presume that their sum is also a uniform RV, but I am not sure about its range.

Can you help me on this.

Thank you so much in advance.
Same here. Is the result mod 2pi? Unfortunately Wikipedia gives two definitions of the mod operator and the answer differs in the two cases. So you are right to be uncertain.

Wikipedia : In computing, the modulo operation returns the remainder or signed remainder of a division, after one number is divided by another.
 

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