Spherical-esque Coordiante System

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Discussion Overview

The discussion revolves around the generalization of spherical coordinate systems from 2D and 3D to N-dimensional spaces. Participants explore how to represent points in higher dimensions using a distance and a series of angles, particularly focusing on the computation of the additional angles required as dimensions increase.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant queries how to define angles in an N-dimensional spherical coordinate system, specifically asking how to compute the angle omega when transitioning from 3D to 4D coordinates.
  • Another participant suggests that defining an angle requires establishing a function between two axes, implying that the added dimension can be arbitrary.
  • A suggestion is made to use the dot product as a method for defining angles in this context.
  • A participant provides a detailed mathematical formulation for converting 4D coordinates into spherical coordinates, illustrating how to compute omega based on projections from lower dimensions.
  • Further clarification is offered on how to generalize the approach, explaining the process of defining angles and projecting into lower-dimensional spaces to derive the coordinates in higher dimensions.

Areas of Agreement / Disagreement

Participants express various methods and reasoning for defining angles in higher dimensions, but there is no consensus on a single approach or formula. Multiple competing views and methods remain present in the discussion.

Contextual Notes

The discussion includes assumptions about the nature of angles and projections in higher dimensions, but these assumptions are not universally agreed upon. The mathematical steps involved in the generalization process are not fully resolved.

LeBrad
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Is there a generalization of the 2D or 3D spherical coordinate system to N-dimensions? I want to represent points in the space as a distance r from something, and then a bunch of angles. If this works for arbitrary dimensions, what's the rule for defining the newest angle each time I add a dimension?

In case that's not clear, what I want to know is, if I have a point in 3D (x,y,z) I can also call it (r,phi,theta). But if I have a point in 4D (x,y,z,w), and I want to call it (r,phi,theta,omega), how do I compute omega?
 
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I don't exactly know for what application you need that, but to define an angle you have to first define a function between two axes. If what you mean is "convert" something N-1 D to N D coordinates, I think you take it as if the added value can be arbitrary.
 
Use the dot product.
 
LeBrad said:
But if I have a point in 4D (x,y,z,w), and I want to call it (r,phi,theta,omega), how do I compute omega?

This is one of doing it:

x=r cos(phi)
y=r sin(phi) cos(theta)
z=r sin(phi) sin(theta) cos(omega)
w=r sin(phi) sin(theta) sin(omega)
 
Ok I think I can see how it generalizes now. If I have a coordinate system for (N-1) D, I can just define an angle between (N-1) space and the Nth dimension, and then project into (N-1) space and then use the (N-1) coordinate system with the projection prepended.

So in 2D we have
x = r*cos(phi)
y = r*sin(phi).
Then when I add a third dimension, I define theta as the angle between the 2D space and the new dimension, then project r onto the 2D space with cos(theta), and get
x = r*cos(theta)*cos(phi)
y = r*cos(theta)*sin(phi). Then project onto the 3rd D to get the final piece,
z = r*sin(theta).

So for 4D I would define omega as the angle between 3D and the 4th D, and let the projection be cos(omega) into 3D to get
x = r*cos(omega)*cos(theta)*cos(phi)
y = r*cos(omega)*cos(theta)*sin(phi)
z = r*cos(omega)*sin(theta)
w = r*sin(omega)
where all I did was prepend cos(omega) to the (N-1) projections and then define the new coordinate as r*sin(omega).
 

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