Opened 4 years ago

Closed 4 years ago

#19472 closed enhancement (fixed)

GLPK backend: More basis status and tableau data functions

Reported by: mkoeppe Owned by:
Priority: major Milestone: sage-6.10
Component: numerical Keywords: lp
Cc: zwang, dimpase, ncohen, vdelecroix, yzh Merged in:
Authors: Aedi Wang Reviewers: Dima Pasechnik
Report Upstream: N/A Work issues:
Branch: 37e90e8 (Commits) Commit: 37e90e85d2e635f929abec54bdc62b17b93184b0
Dependencies: Stopgaps:

Description (last modified by mkoeppe)

This is a follow-up to #18685, #18732.

It adds get_row_prim, set_row_stat, set_col_stat, warm_up.

These are the remaining functions necessary to implement #18804.

Change History (9)

comment:1 Changed 4 years ago by mkoeppe

  • Type changed from PLEASE CHANGE to enhancement

comment:2 Changed 4 years ago by mkoeppe

  • Description modified (diff)

comment:3 Changed 4 years ago by zwang

  • Branch set to u/zwang/GLPK_backend_More_basis_status_and_tableau_data_functions

comment:4 Changed 4 years ago by mkoeppe

  • Cc dimpase ncohen vdelecroix yzh added
  • Commit set to 37e90e85d2e635f929abec54bdc62b17b93184b0
  • Status changed from new to needs_review

New commits:

​37e90e8More basis status and tableau data functions

comment:5 follow-up: Changed 4 years ago by dimpase

Is it possible to add a short explanation of (and a reference) what "warming up the basis" means?

And another question - will there be any frontend functions available to take advantage of this stuff, or it's got to be backend-specific?

comment:6 in reply to: ↑ 5 Changed 4 years ago by mkoeppe

Replying to dimpase:

Is it possible to add a short explanation of (and a reference) what "warming up the basis" means?

The GLPK manual offers this explanation: "This operation includes computing factorization of the basis matrix (if it does not exist), com- puting primal and dual components of basic solution, and determining the solution status." I'm not sure if it's worth adding it.

And another question - will there be any frontend functions available to take advantage of this stuff, or it's got to be backend-specific?

Our current plan is to expose these functions only through a simplified interface that we call "LPBackendDictionary" (#18804), which offers a naive "textbook-style" view on the simplex solvers.

A full-featured frontend interface would be rather tricky. OSI tried that and I'm not sure it really succeeded.

comment:7 Changed 4 years ago by dimpase

  • Status changed from needs_review to positive_review

OK.

comment:8 Changed 4 years ago by dimpase

  • Reviewers set to Dima Pasechnik

comment:9 Changed 4 years ago by vbraun

  • Branch changed from u/zwang/GLPK_backend_More_basis_status_and_tableau_data_functions to 37e90e85d2e635f929abec54bdc62b17b93184b0
  • Resolution set to fixed
  • Status changed from positive_review to closed
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