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Text File  |  1992-08-17  |  2.1 KB  |  48 lines
  1. Newsgroups: sci.math.research
  2. Path: sparky!uunet!wupost!sdd.hp.com!ux1.cso.uiuc.edu!news.cso.uiuc.edu!usenet
  3. From: shillsp@leonardo.cs.curtin.edu.au (Stephen Hill)
  4. Subject: linear programming HELP REQUIRED
  5. Message-ID: <shillsp.714123927@marsh>
  6. Sender: Daniel Grayson <dan@math.uiuc.edu>
  7. X-Submissions-To: sci-math-research@uiuc.edu
  8. Organization: Curtin University of Technology
  9. X-Administrivia-To: sci-math-research-request@uiuc.edu
  10. Approved: Daniel Grayson <dan@math.uiuc.edu>
  11. Date: Tue, 18 Aug 1992 07:45:27 GMT
  12. Keywords: linear programming
  13. Lines: 33
  14.  
  15.  
  16.  
  17. Currently I am working on the Vehicle Routing Problem under
  18. Capacity constraints. I am using a cutting planes technique
  19. to get lower bounds which are then incorporated
  20. in a branch and bound technique. I have programmed
  21. the dual and revised simplex with upper bounds, using an LU
  22. decomposition to solve equations involving the basis, and these both
  23. work for problems with around 450 variables and 50 constraints.
  24.  
  25. With larger problems I encounter numerical instability and cannot
  26. get a solution.
  27.  
  28. I am looking for ways to get rid of this problem. Alternatively I am
  29. willing to purchase a linear programming package, either commercial
  30. or otherwise (to run on a Sun SPARC station 2) or working source code
  31. which I can incorporate into my own code. 
  32.  
  33. I hope that someone out there can provide me with references, advice or
  34. code. Thanks in advance. 
  35.  
  36. ------------------------------------------------------------------------------
  37.                  Stephen Hill- shillsp@euler.cs.curtin.edu.au                  
  38.  
  39.                  Curtin University, Perth, Western Australia                  
  40. ------------------------------------------------------------------------------
  41. --
  42. ------------------------------------------------------------------------------
  43.                  Stephen Hill- shillsp@euler.cs.curtin.edu.au                  
  44.                                                                                 
  45.                  Elvis: Too young to die, too fat to live!                     
  46. ------------------------------------------------------------------------------
  47.  
  48.