<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Dear Marco,<br>
<br>
I take a look at your linear program. I think that the problem may
be related to numerical precision:<br>
<br>
In your constraint matrix there are coefficients such as<br>
<br>
0.000000815218676787828980000000 Buy_A_100032<br>
as well:<br>
BuyOpBigM_A_100032: Buy_A_100032
-124770.535999999990000000000000000000 BuyOp_A_100032 <= 0<br>
<br>
Usually all (fast) linear programming solvers are imprecise due to
hardware limitations.<br>
If your applications needs accurate solutions with precision up to,
lets say, the tenth decimal place, you will probably face some
numerical difficulties.<br>
The problems becomes more prominent when large coefficients are
mixed with very small ones, which is the specific case of your
matrix. These matrixes are called "ill conditioned".<br>
<br>
Solutions:<br>
- you may try to scale your matrix: i.e.: multiply some rows by a
constant<br>
- some solvers have an "exact arithmetic mode", but these modes are
usually hundreds of times slowers (glpk has the parameter --exact,
if I remember correctly).<br>
<br>
Cheers<br>
<br>
Haroldo<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 01-03-2016 12:23, mg wrote:<br>
</div>
<blockquote
cite="mid:CAOayR=ZoZD8-c5zEZq9-jqLij755OZ9r7Pf=-sw8mTH8OCJGjA@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_quote">
<div dir="ltr">Hi All,
<div>I'm facing a crash (std::bad_alloc) solving a MIP
problem.</div>
<div>Attached you can find the zipped lp file causing the
problem and the C++ code I used to load and solve it.</div>
<div><br>
</div>
<div>Cbc version 2.9.8 stable, on Windows</div>
<div><br>
</div>
<div>Problem seems located here (location is approximated
since I could only see mangled code in visual studio) :</div>
<div><span style="font-family:monospace,monospace">ClpNode
--> gutsOfConstructor --> ClpFactorization</span><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><font face="arial, helvetica, sans-serif">Thanks in
advance,</font></div>
<div><font face="arial, helvetica, sans-serif">Marco</font></div>
</div>
</div>
<br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Cbc mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Cbc@list.coin-or.org">Cbc@list.coin-or.org</a>
<a class="moz-txt-link-freetext" href="http://list.coin-or.org/mailman/listinfo/cbc">http://list.coin-or.org/mailman/listinfo/cbc</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
==================================================
Haroldo Gambini Santos
D.Sc, Computer Science
Universidade Federal de Ouro Preto
<a class="moz-txt-link-freetext" href="http://www.decom.ufop.br/haroldo/">http://www.decom.ufop.br/haroldo/</a></pre>
</body>
</html>