How to Compute r in Stereographic Projection from R^4 to R^3?

Click For Summary

Discussion Overview

The discussion revolves around computing the parameter r in the context of stereographic projection from R^4 to R^3. Participants explore the mathematical formulation and visualization challenges associated with this projection, comparing it to similar concepts in R^3.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes a set of equations for stereographic projection in R^4 but expresses uncertainty about computing r and visualizing it.
  • Another participant questions whether the equations represent stereographic projection or spherical coordinates.
  • A different participant recalls a previous example in R^3 where r was computed geometrically and wonders if a similar formula exists in R^4.
  • One participant asserts that stereographic projection is consistent across dimensions and suggests a method involving drawing lines from the north pole to points on the sphere to find intersections with a hyperplane.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct formulation of the projection or the method for computing r. Multiple competing views and interpretations of the projection exist.

Contextual Notes

The discussion highlights potential limitations in visualizing higher-dimensional projections and the reliance on geometric intuition from lower dimensions. There are unresolved questions regarding the applicability of previous methods from R^3 to R^4.

whattttt
Messages
18
Reaction score
0
I am computing a stereographic projection in R^4 and i think i am correct in setting
x=rcos(x)sin(y)
y=rsin(x)sin(y)
z=rcos(y)
but can't see how to compute r as I do not know to visualise it graphically as was possible in R^3, any help would be greatly appreciated
 
Physics news on Phys.org
That doesn't look like stereographic projection to me...do you mean spherical?
 
No. In a previous example it was in R^3 and polar coordinates were used with x=rcosx and y=rsinx and r was computed from the diagram and equaled something like 2tan(pi-theta) which could be computed from the diagram by projection onto the x-axis but I'm not sure if such a formula exists in R^4
 
whattttt said:
I am computing a stereographic projection in R^4 and i think i am correct in setting
x=rcos(x)sin(y)
y=rsin(x)sin(y)
z=rcos(y)
but can't see how to compute r as I do not know to visualize it graphically as was possible in R^3, any help would be greatly appreciated

Stereographic projection is the same in all dimensions. Draw straight lines from the north pole through the points of the sphere and calculate the intersection of these lines with the hyperplane that is perpendicular to the direction of the north pole. You do not need polar coordinates for this.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 39 ·
2
Replies
39
Views
5K
Replies
3
Views
4K
  • · Replies 8 ·
Replies
8
Views
5K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 12 ·
Replies
12
Views
5K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 2 ·
Replies
2
Views
4K