interactive_simplex_method: Improve support for base fields other than QQ, RDF

[mkoeppe]

We remove the ad-hoc conversion of data to RDF in InteractiveLPProblem.feasible_set. This is outdated and problematic:

• the polyhedra code over RDF is not robust at all
• Sage has good support for algebraic polyhedra via normaliz.

We also make the printing code in _latex_product more robust:

• it no longer relies on SR to decide whether a coefficient needs to be wrapped in parens; instead, we use the same simple test that sage.misc.repr.coeff_repr already uses
• recognizing trivial coefficients (0, 1) is switched to comparing text instead of comparing elements - in order to support fields such as SR where == is magic

CC: @yuan-zhou @novoselt

Component: linear programming

Author: Matthias Koeppe, ...

Issue created by migration from https://trac.sagemath.org/ticket/31312

[mkoeppe]

Branch: u/mkoeppe/interactive_simplex_method__improve_support_for_base_fields_other_than_qq__rdf

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: f5dd363

[mkoeppe]

New commits:

523a1d5	InteractiveLPProblem.feasible_set: Remove coercion to floating point - no longer needed now that algebraic polyhedra are supported in Sage
fe4b405	sage.numerical.interactive_lp._latex_product: Make use of parens around a coefficient depend on the same test that sage.misc.repr.coeff_repr uses
86ebce6	src/sage/numerical/interactive_simplex_method.py (_latex_product): Do not compare coefficients with 0, compare latex representation with 0 instead
f5dd363	_latex_product: Compare latex with '1' instead of comparing coefficient directly

[mkoeppe]

Changed author from Matthias Koeppe to Matthias Koeppe, ...

[mkoeppe]

comment:3

This probably needs some additional tests to make sure that the changes do not break problems with RDF data (which I never use)

[mkoeppe]

comment:4

It would also be good to add a keyword argument backend to feasible_set which would be passed to the polyhedron constructor.

[mkoeppe]

comment:5

Sage development has entered the release candidate phase for 9.3. Setting a new milestone for this ticket based on a cursory review of ticket status, priority, and last modification date.

[mkoeppe]

Removed branch from ticket description; replaced by PR #37865.