Add range minimum query kernels #1764
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ginkgo-bot
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my first impression on turning |
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L includes fill-in, A does not |
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Overall, a lot more documentation is necessary. Especially what the new classes in bit_packed_storage and range_minumum_querry are there for, and how they work together.
At least I can't properly review it right now, since there is too little information on what functions/classes are supposed to do.
Constexpr evaluation complexity too high
Co-authored-by: Marcel Koch <[email protected]>
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| /** Returns the ballot number C(p, q). */ |
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Is it possible to describe in a few words the meaning of C(p, q) in this context?
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I don't think there is any particularly useful description I could add here, beyond the definition above.
upsj
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This adds a data structure to answer queries of the kind$\text{argmin}_{i \in [a,b]} \text{array}[i]$ in constant time. This will be used to speed up the computation of LCAs in the symbolic Cholesky algorithm, turning the counting step from $O(nnz(L))$ algorithm to a $O(nnz(A))$ algorithm.
The corresponding Wikipedia articles describe the algorithms pretty well https://en.wikipedia.org/wiki/Range_minimum_query, the constant time query is described in more detail in J. Fischer and V. Heun, “Space-Efficient Preprocessing Schemes for Range Minimum Queries on Static Arrays,” SIAM J. Comput., vol. 40, no. 2, pp. 465–492, Jan. 2011, doi: 10.1137/090779759.
TODO: