slightly faster Moebius matrix for posets

[fchapoton]

CC: @tscrim @jm58660

Component: combinatorics

Author: Frédéric Chapoton

Branch/Commit: dece8f6

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/28551

[fchapoton]

Commit: dece8f6

[fchapoton]

New commits:

dece8f6

faster Moebius matrix for posets

[fchapoton]

Branch: u/chapoton/28551

[fchapoton]

comment:2

Before:

sage: P=posets.TamariLattice(7)
sage: %time P.moebius_function_matrix()
CPU times: user 606 ms, sys: 553 µs, total: 607 ms
Wall time: 606 ms
429 x 429 dense matrix over Integer Ring (use the '.str()' method to see the entries)

After:

sage: P=posets.TamariLattice(7)
sage: %time P.moebius_function_matrix()
CPU times: user 359 ms, sys: 3.85 ms, total: 362 ms
Wall time: 362 ms
429 x 429 dense matrix over Integer Ring (use the '.str()' method to see the entries)

[tscrim]

comment:3

It is a more memory intensive version, but I don't think it is too significant, especially compared to the speedup. LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[vbraun]

Changed branch from u/chapoton/28551 to dece8f6