[Osi] Fwd: crossover step

[John J Forrest]

Matt,

I have added some code to OsiClp.  A very simple example of its use is in
Cbc/examples!!  I know that is the wrong place, but there is nowhere to put
a OsiClp specific example.

John


                                                                                          
  From:       Matthew Galati <magh at lehigh.edu>                                            
                                                                                          
  To:         John J Forrest/Watson/IBM at IBMUS, Matthew Galati <matthew.galati at sas.com>    
                                                                                          
  Date:       10/07/2009 12:24 AM                                                         
                                                                                          
  Subject:    Re: Fwd: crossover step                                                     
                                                                                          





I looked at the code where you do crossover - and there is quite a bit of
logic there. And it also seems tied into the barrier data structs. Is it
possible for you to create a function in OsiClp that takes in a current
solution and forms a basis from that? I.e., basically a warm start for
OsiClp but in the form of a primal solution, not a basis.



  Matt,

  Code is in ClpSimplex:initialSolve which confusingly is in ClpSolve.cpp
  as ClpSolve controls options. Round about 2032 is where code returns from
  barrier.

  By the way, many bugs have been fixed (not exactly by mistake) in trunk.
  Do you know if things work better with trunk? I will try and get a new
  stable by early December.

  John

  Inactive hide details for Matthew Galati ---10/05/2009 05:29:44 PM---Hi
  John - do you think this is possible using CLP? I assumMatthew Galati
  ---10/05/2009 05:29:44 PM---Hi John - do you think this is possible using
  CLP? I assume you do something like this for interior



                                                                           
                                                                           
                                                                           
                                                                           
 From:                   Matthew Galati <magh at lehigh.edu>                  
                                                                           
                                                                           
 To:                     John J Forrest/Watson/IBM at IBMUS                   
                                                                           
                                                                           
 Date:                   10/05/2009 05:29 PM                               
                                                                           
                                                                           
 Subject:                Fwd: crossover step                               
                                                                           






  Hi John - do you think this is possible using CLP? I assume you do
  something like this for interior point to crossover to simplex? Can you
  point me to where in your code you do this and any suggestion on how I
  can extract that to do it from OSI layer?

  Thanks in advance,
  Matt

  ---------- Forwarded message ----------
  From: Matthew Galati <magh at lehigh.edu>
  Date: Mon, Sep 7, 2009 at 11:51 PM
  Subject: crossover step
  To: clp at list.coin-or.org


  After interior completes - it can/does(?) do a crossover step and then
  completes with simplex. Can someone point me to the piece of code that
  does the crossover step in CLP?

  I am assuming there is no Osi interface for this (crossover)? It would be
  nice if there was.

  Thanks,
  Matt



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