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Maths - 2D Clifford / Geometric Algebra

Description

On the previous pages we showed that from a two dimensional vectors we generate an algebra with 4 elements (e, e1, e2and e1^e2) .

basis grade
e scalar
e1, e2 vector
e1^e2 bivector (in this case a scalar value)

We can define a general 'number' in this algebra as a linear sum of these basis:

a + b e1 + c e2+ d e1^e2

We will call this 'number' a multivector, and for 2D vectors is is defined by the 4 scalar values here denoted by a,b,c and d.

In order to understand the properties of this algebra we need to look at the arithmetic rules here.

grade  2 diamond

Such an algebra is the smallest, non-trivial clifford algebra so this may be a good chance to experiment with what we can change.

For instance, we can try changing the following aspects of the algebra:

These options are discussed on this page.

Comparison of 2D multivector with Quaternion

Clifford algebras based on 2D vectors have 4 'dimensions' so how do they compare with quaternions which also have 4 dimensions? this is discussed on this page.


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see also:
Correspondence about this page

Book Shop - Further reading.

Where I can, I have put links to Amazon for books that are relevant to the subject, click on the appropriate country flag to get more details of the book or to buy it from them.

cover Clifford Algebra to Geometric Calculus: A Unified Language for Mathematics and Physics (Fundamental Theories of Physics). This book is intended for mathematicians and physicists rather than programmers, it is very theoretical. It covers the algebra and calculus of multivectors of any dimension and is not specific to 3D modelling.

cover New Foundations for Classical Mechanics (Fundamental Theories of Physics). This is very good on the geometric interpretation of this algebra. It has lots of insights into the mechanics of solid bodies. I still cant work out if the position, velocity, etc. of solid bodies can be represented by a 3D multivector or if 4 or 5D multivectors are required to represent translation and rotation.

Other Math Books

Commercial Software Shop

Where I can, I have put links to Amazon for commercial software, not directly related to the software project, but related to the subject being discussed, click on the appropriate country flag to get more details of the software or to buy it from them.

cover Mathmatica

Can you help?

Please send me any improvements to here. I would appreciate ideas to make the pages more useful including error correction, ideas for new pages, improvements to wording. It helps if you quote the full URL of the page.

Could anyone let me know of a good proof that a quaternion multiplication can be used to represent a rotation in 3 dimensions, I'm not looking for the shortest proof, but the most easily understood.

Terminology and Notation

Specific to this page here:

 

program

I am working on a project which uses these principles, if you would like to help me with this you are welcome to join in, here:

http://sourceforge.net/projects/mjbworld/

This site may have errors. Don't use for critical systems.

Copyright (c) 1998-2008 Martin John Baker - All rights reserved - privacy policy.