Changes between Version 1 and Version 7 of Ticket #22701
 Timestamp:
 Sep 30, 2018, 5:53:51 AM (4 years ago)
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Ticket #22701

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Status
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new
toneeds_review

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Authors
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Matthias Koeppe
 Property Cc moritz novoselt tscrim added

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Summary
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Setting up a Polyhedron from both Vrep and Hrep
toSetting up a Polyhedron from both Vrep and Hrep  for backend='field'

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u/mkoeppe/setting_up_a_polyhedron_from_both_vrep_and_hrep

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sage8.0
tosage8.4

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6d91f255cacaf7fb89b3a8ad1ebcc470e7ef7437

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Ticket #22701 – Description
v1 v7 1 1 Currently, only one of the two is allowed. 2 For at least some backends (certainly, the generic (`"field"`) backend and polymake (#22683)), it makes sense to initialize with both if they are known, to avoid expensive recomputation. 2 For at least some backends (certainly, the generic (`"field"`) backend and polymake (#22683)), it makes sense to initialize with both if they are known, to avoid expensive recomputation. (This could also be the basis of code that delegates to a particular backend for particular features.) 3 3 Users should also be allowed to indicate whether the given presentations are already minimal. 4 4 5 In particular this could help to implement a fast version of `change_backend()` (#22575) and could be the basis of code that delegates to a particular backend for particular features. 5 In this ticket, we implement this for `Polyhedron_field`, enabling fast `base_extend`. 6 7 When both Vrep and Hrep are given, they must be minimal; the interface is designed to allow for future extensions. 8 9 The toplevel constructor `Polyhedron` is unchanged in this ticket. It is still an error if `Polyhedron(vertices=..., inequalities=...)` is attempted. 10 11 Without this ticket: 12 {{{ 13 sage: p = polytopes.hypercube(6, backend='ppl') 14 sage: %time q = p.base_extend(AA) 15 CPU times: user 2.27 s, sys: 10.3 ms, total: 2.28 s 16 Wall time: 2.28 s 17 sage: q 18 A 6dimensional polyhedron in AA^6 defined as the convex hull of 64 vertices 19 }}} 20 21 With this ticket: 22 {{{ 23 CPU times: user 13.4 ms, sys: 603 µs, total: 14 ms 24 Wall time: 14.9 ms 25 }}} 26 6 27 7 28 Related: