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| author | Tom Smeding <tom@tomsmeding.com> | 2026-01-26 23:37:55 +0100 |
|---|---|---|
| committer | Tom Smeding <tom@tomsmeding.com> | 2026-02-12 20:44:06 +0100 |
| commit | c2831ef0f8be71f2a72ee4eee446e2ac473fb638 (patch) | |
| tree | fd5d8b38aa3920174689f14f9817f8fdaf9e3cb6 /src/CHAD/Drev.hs | |
| parent | f5b1b405fa4ba63bdffe0f2998f655f0b06534bf (diff) | |
Multihot cotangents WIP (doesn't work)
The idea is sound but for a smaller source language. Notes also in
Obsidian, but the theory so far is that dropping support for nested
arrays makes this possible, although making the result type-safe (i.e.
not have partial functions in a bunch of places) would require making
the lack of nested array support explicit in the embedded type system,
i.e. have Accelerate-like stratification.
The point is that multihots can be added heterogeneously using
plusSparseS but not homogeneously with EPlus or plusSparse, because the
indices might differ between the summands. Thus as long as we never need
to homogeneously sum multihot cotangents, we're golden.
Now the crucial observation is that we only need plus to be homogeneous
on array elements. So if array elements cannot themselves be arrays,
i.e. we drop support for nested arrays, no homogeneous plus of multihot
array cotangents is needed, and we can have static multihots.
Diffstat (limited to 'src/CHAD/Drev.hs')
| -rw-r--r-- | src/CHAD/Drev.hs | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/src/CHAD/Drev.hs b/src/CHAD/Drev.hs index 9f2921c..33dece7 100644 --- a/src/CHAD/Drev.hs +++ b/src/CHAD/Drev.hs @@ -1009,11 +1009,10 @@ drev des accumMap sd = \case let smallE = unsafeWeakenWithSubenv usedSub e in subDescr des usedSub $ \usedDes subMergeUsed subAccumUsed subD1eUsed -> case drev usedDes (VarMap.subMap subAccumUsed accumMap) sd smallE of { Ret e0 subtape _ sub e2 -> - let subMergeUsed' = subenvMap (\t Refl -> spDense t) (d2eM (select SMerge des)) (subenvD2E subMergeUsed) in Ret (collectBindings (desD1E des) subD1eUsed) (subenvAll (desD1E usedDes)) (weakenExpr (wSinks (desD1E usedDes)) $ drevPrimal des e) - (subenvCompose subMergeUsed' sub) + (subenvCompose (subenvD2E subMergeUsed) sub) (letBinds (fst (weakenBindingsE (WSink .> wRaiseAbove (desD1E usedDes) (d2ace (select SAccum des))) e0)) $ weakenExpr (autoWeak (#d (auto1 @sd) |