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Dear Mahdi,<br>
<br>
even if you create a model with only linear constraints, SCIP might
upgrade them in presolving to specialized linear constraints like
knapsack or set cover constraints. SCIP does not do this if you
marked a constraint to be modifiable, which you should have done if
priced variables will potentially be added to the constraint. On the
other hand, if you will not add any priced variables to the
constraint, you don't need to mark it to be modifiable, but you
should also not need its dual value.<br>
<br>
I would suggest you check what type the constraint has via
SCIPconshdlrGetName(SCIPconsGetHdlr(cons)) either in gdb or in your
code.<br>
<br>
Best,<br>
Gerald<br>
<br>
<div class="moz-cite-prefix">On 22.05.19 14:45, mahdi noorizadegan
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAH4sNwq8U+p4R8o=o1C7Ukw6JEUe4iWvgi5pjDdi7bg13EOqig@mail.gmail.com">
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<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">Hello,</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d"><br>
</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">I am
implementing an IP using branch and price method.</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">When I want to
get the dual value of constraints which are all linear, I get
the following error</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d"><br>
</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">[src/scip/cons_linear.c:17033]
ERROR: constraint is not linear</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d"><br>
</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">What can be
wrong?</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d"><br>
</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">Looking
forward to hearing from you,</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">Regards,</div>
<div class="gmail_default"
style="font-family:georgia,serif;color:#20124d">Mahdi<br>
</div>
</div>
<br>
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