Martin Baker wrote:
> I have put a rewritten version of CliffordAlgebra here:
>
> http://github.com/martinbaker/multivector/
>
> Would you consider putting this into FriCAS?
>
> This works with a non-orthogonal basis unlike the existing code which
> gives incorrect results.
>
Yes, we certainly want handle non-orthogonal basis. I had no time
to look deeper, but AFAICS there are at least small problems to fix:
1) Description: the formula e[i]*e[j] = -e[j]*e[i] is valid only
for orthogonal basis. General rule for symmetric forms is
u^2 = Q(u). I am not sure about non-symmetric case.
2) Comment 'eFromBinaryMap(n) sets the appropriate unit elements' is
misleading. From code it is clear that it produces corresponding
element of basis, but 'unit element' in a ring typically means
something quite different. And formulas in the comment look
wrong in non-orthogonal case.
Also, it would be good to compare speed of current code and your
version. Orthogonal case is doing much simpler computation, so
it may be faster. If that is the case then it makes sense to
keep current code (renamed) and implement a switch so that
non-orthogonal case is done by your code but orthognal one
by old. Of course, if there is no significant difference in
speed (or your is faster) then we will just replace old version.
BTW: At the URL you gave I can view code, but it inside HTML
markup. How I can fetch the source? Given that it is github
I guess 'git....' but what I should put in place of dots?
--
Waldek Hebisch
[email protected]
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