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Wait, there are a lot of ways in computer science to choose points randomly, and points randomly with constraints (here belong to unit sphere) and that could ch
by ttoinou 8y ago
Wait, there are a lot of ways in computer science to choose points randomly, and points randomly with constraints (here belong to unit sphere) and that could change the result, no ?
- pathsjs 8y agoIn fact the result has little to do with computer science - it is purely a mathematical result. The way points are sampled (uniform distribution) is clarified in the text
- kgwgk 8y agoIt won't change the result if you're doing it correctly.
- imh 8y ago>We’ll be ‘randomly choosing’ lots of points on spheres of various dimensions. Whenever we do this, I mean that they’re chosen independently, and uniformly with respect to the unique rotation-invariant Borel measure that’s a probability measure on the sphere. In other words: nothing sneaky, just the most obvious symmetrical thing! There are an infinite number of probability distributions over most objects, yes, but there's also often a good default that is the "uniform" distribution. That's what they're talking about here.
- OscarCunningham 8y agoAs an aside, there's an interesting way to generate a uniform distribution on a sphere. It uses the fact that the joint distribution of several independent standard Gaussians has rotational symmetry. So to generate a random point on the surface of the n-sphere, you can sample n+1 numbers independently from the standard Gaussian and then normalise them so that their squares sum to 1 (if they're all 0 then you have to reroll).
- crasshopper 8y agoPersi Diaconis https://www.ams.org/notices/200511/what-is.pdf https://www.ams.org/notices/200511/what-is.pdf — you want to choose randomly from the eigenvalues of a matrix