<br><font size=2 face="sans-serif">Ulrich,</font>
<br>
<br><font size=2 face="sans-serif">What do you mean by the row being at
its upper bound?</font>
<br>
<br><font size=2 face="sans-serif">Clp uses row activities so activity
= sum a sub ij * x sub j. So there is an implicit -1 - CoinWarmStart
thinks in terms of +1 so L and U are flipped. Both are correct.</font>
<br>
<br><font size=2 face="sans-serif">John Forrest</font>
<br>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>Ulrich Spoerlein <spoerlein@informatik.uni-wuerzburg.de></b>
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<br><font size=1 face="sans-serif">Sent by: coin-lpsolver-bounces@list.coin-or.org</font>
<p><font size=1 face="sans-serif">10/18/2005 06:01 AM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td valign=top><font size=1 face="sans-serif">coin-lpsolver@list.coin-or.org</font>
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<div align=right><font size=1 face="sans-serif">cc</font></div>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">[Coin-lpsolver] Bug in RowStatus:
Lower vs. Upper Bound</font></table>
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<br><font size=2><tt>Good morning everyone,<br>
<br>
There is a bug in CLP which I was unable to find yet. The symptoms are<br>
as follows:<br>
<br>
ClpSimplex::getRowStatus() is returning '3' (==atLowerBound) when in<br>
fact the row is at it's upper bound, as can be seen from the solution or<br>
from the basis.<br>
<br>
I printed all the column and row stats and the basis, the whole document<br>
is at [1].<br>
<br>
It looks roughly like this:<br>
getBasis().print() shows these columns<br>
BLBLLBLLLBLLBLBBBLBBL...<br>
and I get these stats from getColumnStatus()<br>
13133133313313111311...<br>
<br>
So this is fine and corresponds to the definition of the Status enum.<br>
<br>
The rows are different:<br>
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBUBBBBUBBBBBBBBBUBB<br>
vs.<br>
111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111311113111111111311<br>
<br>
So getBasis() tells me, some are at the upper bound (which in fact they<br>
are!) but getRowStatus() is returning 3 which is defined as<br>
"atLowerBound".<br>
<br>
I have no clue to what's going on here.<br>
<br>
Another thing: Shouldn't fixed cols/rows be printed as 'F' by getBasis()<br>
and not as 'U' or 'L'?<br>
<br>
[1] http://www.galgenberg.net/~q/clp_basis.txt<br>
<br>
Ulrich Spoerlein<br>
-- <br>
PGP Key ID: F0DB9F44
Encrypted mail welcome!<br>
Fingerprint: F1CE D062 0CA9 ADE3 349B 2FE8 980A C6B5 F0DB 9F44<br>
Ok, which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn."<br>
didn't you understand?<br>
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</tt></font>
<br>