<br><font size=2 face="sans-serif">Sorry - I was thinking of the tableau
methods. </font>
<br>
<br><font size=2 face="sans-serif">getBInvRow was correct - but did not
allow for scaled matrices. getBInvCol needed some sign changes.</font>
<br>
<br><font size=2 face="sans-serif">The sign changes were easy - doing scaling
was not so easy - hope it is correct.</font>
<br>
<br><font size=2 face="sans-serif">I would suspect that not many people
have tried these methods and use tableau methods instead.</font>
<br>
<br><font size=2 face="sans-serif">John Forrest</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=40%><font size=1 face="sans-serif"><b>John J Forrest/Watson/IBM@IBMUS</b>
</font>
<br><font size=1 face="sans-serif">Sent by: coin-lpsolver-bounces@list.coin-or.org</font>
<p><font size=1 face="sans-serif">09/16/2005 12:47 PM</font>
<td width=59%>
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<td>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td valign=top>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td valign=top><font size=1 face="sans-serif">coin-lpsolver@list.coin-or.org</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">Re: [Coin-lpsolver] problems
with BInvCol and BInvRow</font></table>
<br>
<table>
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<td>
<td></table>
<br></table>
<br>
<br>
<br><font size=2 face="sans-serif"><br>
Clp stores slacks as -1.0 (i.e. not really slack but row activity). There
is a comment about this in OsiClpsolverInterface but something is obviously
wrong. CglGomory.cpp uses CoinFactorization directly so does not
have this problem.</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
I will try and look at it this weekend.</font><font size=3> <br>
</font><font size=2 face="sans-serif"><br>
John Forrest</font><font size=3> <br>
<br>
</font>
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<td width=44%><font size=1 face="sans-serif"><b>Anureet Saxena <anureet@yahoo.com></b>
<br>
Sent by: coin-lpsolver-bounces@list.coin-or.org</font><font size=3> </font>
<p><font size=1 face="sans-serif">09/15/2005 05:34 PM</font><font size=3>
</font>
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<br>
<table width=100%>
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<td width=15%>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td width=84% valign=top><font size=1 face="sans-serif">coin-lpsolver@list.coin-or.org</font><font size=3>
</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td valign=top>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">[Coin-lpsolver] problems
with BInvCol and BInvRow</font></table>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=49%>
<td width=50%></table>
<br></table>
<br><font size=3><br>
<br>
<br>
hi,<br>
<br>
There seems to be some trouble with the <br>
OsiSimplexInterface::getBInvCol() and<br>
OsiSimplexInterface::getBInvRow() functions.<br>
<br>
In particular, constructing the basis inverse via these two functions gives<br>
different results (after transposing). Furthermore, the problem is specifically<br>
in those rows whose corresponding basic variable is a slack variable. <br>
<br>
A small example (3 rows and 5 variables) and relevent code can be downloaded<br>
from the following link:</font><font size=3 color=blue><u><br>
<br>
</u></font><a href=http://www.andrew.cmu.edu/user/anureets/tmp/ target=_blank><font size=3 color=#003399><u>http://www.andrew.cmu.edu/user/anureets/tmp/</u></font></a><font size=3><br>
File Name: BInvCol_case.tgz<br>
<br>
It will be very nice if someone could point out and/or rectify the error.
<br>
<br>
On a different note, OsiSimplexInterface has a function: <br>
<br>
enableSimplexInterface(bool doingPrimal). <br>
<br>
The role of the parameter "doingPrimal" is not adequately described
in the doxygen documentation. Could someone please give some idea as to
what this parameter accomplishes. <br>
<br>
<br>
regards,<br>
Anureet Saxena<br>
ACO Doctoral Student,<br>
Tepper School of Business,<br>
Carnegie Mellon University.<br>
<br>
<br>
<br>
<br>
Anureet Saxena<br>
anureet@cmu.edu<br>
anureet@yahoo.com<br>
<br>
--This mail was delivered to you on 100% recyclable electrons. </font>
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