Let's remove Quaternions from every 3D Engine
Texts on GA seem to start out saying &quot;we&#x27;re going to replace vector analysis with something intuitive and natural and eloquent and...&quot; and then immediately introduce the &quot;geometric product&quot;, which is neither intuitive, eloquent, or, as far as I can tell, natural. Its properties are found via formula-wrangling, and the results you get from it seem to just magically work, rather than being intuitive.<p>Bivectors in general are conceptually great; it&#x27;s just the geometric product which I think is conceptually flimsy.  And it&#x27;s surprisingly hard to compute or make sense of the geometric product in general which is why the writer of the first book cited on the OP wrote &quot;I do not think it possible to give a quick definition of the general geometric product.&quot;[1]<p>As far as I can tell 95% of the usefulness of geometric algebra is the usefulness of the <i>wedge</i> product ∧, which is absolutely under-appreciated and appears in loads of places in disguise (for instance, the determinant of a matrix is the wedge product of all of its rows or columns together).<p>The last 5% of the usefulness of GA comes from using the geometric product in vector-rotation via -ava^-1, which is admittedly very useful (it&#x27;s why physics and computer graphics represent rotation this way, albeit in disguised forms like Pauli matrices and quaternions.) You can express that form without the geometric product, but I haven&#x27;t found a way that strikes me as very elegant.<p>I don&#x27;t mean to condemn GA - I think what it&#x27;s doing is massively important. The mathematical language for vector analysis deficient compared to what we could be using, and a lot of things are  more intuitive and natural in better language. I just suspect that the, uh, ideal form of this stuff will look slightly different than GA, and might not include the geometric product at all, but will definitely include the wedge product absolutely everywhere.<p>(I&#x27;ve spent a lot of free time trying to figure this out but I don&#x27;t really have a compelling result yet. I&#x27;ve been meaning to try blogging about it, though, since it&#x27;s basically my favorite thing to study.)<p>[1] <a href="https:&#x2F;&#x2F;math.stackexchange.com&#x2F;questions&#x2F;444988&#x2F;looking-for-a-clear-definition-of-the-geometric-product" rel="nofollow">https:&#x2F;&#x2F;math.stackexchange.com&#x2F;questions&#x2F;444988&#x2F;looking-for-...</a>