Dear All,
I really need your help regarding a MIQCP in CPLEX. I formulated the problem and then tried to solve it in CPLEX but I am getting the following error:
"CPLEX Error 5002: Q in 'id182' is not positive semidefinite."
Is there any way to deal with this issue. I mean, if the constraints are not positive semidefinite, can we still solve the problem in CPLEX?
I really appreciate your help. If you want me to send the code, I will send it. Here are some of the constraints:
sum (t in Periods) X[t] Y[t]== sum (t in Periods) N[t];* where X[t] is a binary decision variable and Y[t] is an integer decision variable.
Topic

Re: Solving MIQCP in CPLEX
20130115T12:19:28ZThis is the accepted answer. This is the accepted answer. SystemAdmin
 20130113T07:34:58Z
The model in CPLEX is attached, any help will be appreciated.
If X[i] is zero then Y[i] must be zero. If X[i] is one then Y[i] must not be larger than 4.
If this is correct for your model you can just add
forall (t in Periods) Y[i] <= 4 * X[i];
and replace the offending constraint by
sum (t in Periods) Y[t]== sum (t in Periods) N[t];
Updated on 20140324T22:41:56Z at 20140324T22:41:56Z by ironman 
Re: Solving MIQCP in CPLEX
20130125T19:24:44ZThis is the accepted answer. This is the accepted answer. SystemAdmin
 20130115T12:19:28Z
Is it OK to have this constraint in your model:
<pre class="java dw" dataeditorlang="java" datapbcklang="java" dir="ltr">If X[i] is zero then Y[i] must be zero. If X[i] is one then Y[i] must not be larger than 4. </pre>
If this is correct for your model you can just add
<pre class="java dw" dataeditorlang="java" datapbcklang="java" dir="ltr">forall (t in Periods) Y[i] <= 4 * X[i]; </pre>
and replace the offending constraint by
<pre class="java dw" dataeditorlang="java" datapbcklang="java" dir="ltr">sum (t in Periods) Y[t]== sum (t in Periods) N[t]; </pre>
I have another question now: I have created a model in CPLEX 12.5 and want to call and solve the model from VBA in Excel, any idea?