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4 commits

Author SHA1 Message Date
Bill Currie
5f22fd07d9 [qfcc] Implement 3d PGA dot products
Also, correct the handling of scalars in dot and wedge products: it
turns out s.v and s^v both scale. However, it seems the CSE code loses
things sometimes.
2023-08-24 15:49:52 +09:00
Bill Currie
c550ab6b86 [qfcc] Switch 2d PGA groups to be easily implemented
I guess Hamish's suggestion made sense at the time, but I found that
with the current instructions, the reversed bivector wasn't so nice to
implement it would need a swizzle as well as the cross-product.
2023-08-23 21:43:14 +09:00
Bill Currie
cfcacfbf28 [qfcc] Use scatter-gather for multivec expressions
This makes working with them much easier, and the type system reflects
what's in the multi-vector. Unfortunately, that does mean that large
algebras will wind up having a LOT of types, but it allows for efficient
storage of sparse multi-vectors:

    auto v = 4*(e1 + e032 + e123);

results in:

    0005 0213 1:0008<00000008>4:void     0:0000<00000000>?:invalid
              0:0044<00000044>4:void          assign (<void>), v
    0006 0213 1:000c<0000000c>4:void     0:0000<00000000>?:invalid
              0:0048<00000048>4:void          assign (<void>), {v + 4}

Where the two source vectors are:

    44:1 0 .imm float:18e [4, 0, 0, 0]
    48:1 0 .imm float:1aa [4, 0, 0, 4]

They just happen to be adjacent, but don't need to be.
2023-08-23 15:38:32 +09:00
Bill Currie
2e91b29580 [qfcc] Start work on implementing geometric algebra
This gets only some very basics working:
 * Algebra (multi-vector) types: eg @algebra(float(3,0,1)).
 * Algebra scopes (using either the above or @algebra(TYPE_NAME) where
   the above was used in a typedef.
 * Basis blades (eg, e12) done via procedural symbols that evaluate to
   suitable constants based on the basis group for the blade.
 * Addition and subtraction of multi-vectors (only partially tested).
 * Assignment of sub-algebra multi-vectors to full-algebra multi-vectors
   (missing elements zeroed).

There's still much work to be done, but I thought it time to get
something into git.
2023-08-21 17:58:20 +09:00