Uniform distribution on the n-sphere.

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SUMMARY

The discussion centers on demonstrating that the random vector $$\underline{W}=\frac{\underline{X}}{\frac{||\underline{X}||}{\sqrt{n}}}$$, where $$X_i \sim N(0,1)$$, has a uniform distribution on the n-sphere with radius $$\sqrt{n}$$. The key insight is that converting to n-dimensional spherical coordinates reveals that the area distribution across the sphere is uniform. The challenge lies in understanding how to derive this uniformity from the cumulative distribution function (CDF).

PREREQUISITES
  • Understanding of random vectors and their properties
  • Familiarity with normal distributions, specifically $$N(0,1)$$
  • Knowledge of n-dimensional spherical coordinates
  • Concept of cumulative distribution functions (CDF)
NEXT STEPS
  • Study the derivation of uniform distributions on n-spheres
  • Learn about the transformation of random variables to spherical coordinates
  • Explore the properties of cumulative distribution functions in multivariate contexts
  • Investigate the implications of area distributions in higher dimensions
USEFUL FOR

This discussion is beneficial for mathematicians, statisticians, and data scientists interested in probability theory, particularly those working with random vectors and geometric distributions in higher dimensions.

MathematicalPhysicist
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Hi, I have the next RV:

$$\underline{W}=\frac{\underline{X}}{\frac{||\underline{X}||}{\sqrt{n}}}$$
where $$X_i \tilde \ N(0,1)$$
It's a random vector, and I want to show that it has a uniform distribution on the n-sphere with radius $$\sqrt{n}$$.

I understand that it has this radius, just calculate it. But I don't understand from calculating the CDF how to I arrive at uniform distribution.

Thanks in advance, MP.
 
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You need to convert to n dimensional spherical coordinates. The "area" distribution should be uniform.
 

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