What are quaternions and ow can they be used?

  • Context: Undergrad 
  • Thread starter Thread starter JungleJesus
  • Start date Start date
  • Tags Tags
    Quaternions
Click For Summary

Discussion Overview

The discussion revolves around quaternions, exploring their definition, mathematical properties, and applications, particularly in computer graphics. Participants seek to understand quaternions in simpler terms and their significance compared to complex numbers and matrix representations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants describe quaternions as an extension of complex numbers, suggesting they are used to represent rotations around different axes using matrix multiplication.
  • One participant notes that quaternions consist of three complex units (i, j, k) and highlights the non-commutative property of their multiplication.
  • Another participant mentions that quaternions have been historically displaced by vector analysis but have seen a revival due to their efficiency in computing spatial rotations.
  • Some participants express uncertainty about the specific reasons quaternions were developed as an extension of complex numbers and question whether they can be considered "super-complex" numbers.
  • The advantages of using quaternions over matrices in computer graphics, such as reduced memory usage and simpler interpolation, are discussed.

Areas of Agreement / Disagreement

Participants generally agree on the utility of quaternions in computer graphics and their mathematical properties, but there remains uncertainty regarding their historical development and the reasons for their necessity as an extension of complex numbers.

Contextual Notes

Some limitations in understanding the historical context of quaternions and their comparison to vector analysis are noted, as well as the unresolved nature of why complex numbers were deemed insufficient.

JungleJesus
Messages
36
Reaction score
0
I've seen quaternions mentioned in a few articles online and I think they could be a very interesting subject. I would like to learn about them in simpler terms first. Can anyone give me the rundown on what they are and how they work?
 
Mathematics news on Phys.org
They are used as a way of describing a rotation around difference axis using matrix multiplication rather than trig and angles.
They probably have some deeper mathematical significance, but mostly they get used to work out how to rotate shapes in computer graphics.

http://en.wikipedia.org/wiki/Quaternions
 
I've heard that quaternions are an extension of the complex numbers. In the same way we had to invent complex numbers to solve all polynomials, quaternions had to be invented to... ?

edit: the wiki page kind of answers my question. I've yet quite been able to pinpoint exactly why complex numbers were unsatisfactory, and why quaternions were needed as an extension. Can these be considered as "super-complex" numbers in a way?

Note:
wikipedia said:
From the mid 1880s, quaternions began to be displaced by vector analysis, which had been developed by Josiah Willard Gibbs and Oliver Heaviside. Vector analysis described the same phenomena as quaternions, so it borrowed ideas and terms liberally from the classical quaternion literature. However, vector analysis was conceptually simpler and notationally cleaner, and eventually quaternions were relegated to a minor role in mathematics and physics.

However, quaternions have had a revival in the late 20th century, primarily due to their utility in describing spatial rotations. Representations of rotations by quaternions are more compact and faster to compute than representations by matrices...
 
Last edited:
JungleJesus said:
I've seen quaternions mentioned in a few articles online and I think they could be a very interesting subject. I would like to learn about them in simpler terms first. Can anyone give me the rundown on what they are and how they work?

Quaternions are the real numbers when you add not one, but three complex units: i, j, k. The notable property is that multiplication doesn't commute: i * j = -j * i, and that i^2 = j^2 = k^2 = ijk.

They are used heavily in computer graphics. Quaternions are an alternate way to represent a rotation. The advantages they offer over matrices is that they take up less space in memory and you can compute rotations in fewer instructions with them. Additionally, given two quaternions, it's very easy to interpolate between them.
 
Thanks for the information. I'll keep looking around for more. If anybody has anything to add, please feel free to do so.
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 8 ·
Replies
8
Views
8K
  • · Replies 24 ·
Replies
24
Views
22K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 6 ·
Replies
6
Views
4K