[SCIP] A question about initial solution of branch and price.

[weikaimas at 163.com]

Hi Matthias,

Thanks for your reply.

I did not attach all my model in the last email. I attach this model in this email.

The model is printed by   SCIP_CALL( SCIPwriteLP(scip, "N_initial_model.lp") ), in my code.

SCIP shows the objective value is 30 (see the picture I attached in my last email).

I checked all my code without finding any mistake.

Would like to give me some suggeations.

Best regard,

Kai Wei.

 
From: Matthias Miltenberger
Date: 2015-11-03 15:55
To: weikaimas at 163.com
CC: scip
Subject: Re: [SCIP] A question about initial solution of branch and price.
Hey Kai Wei,

I do not see how the model you described corresponds to the SCIP output you sent us. Where are the 337 constraints coming from?
I suppose there's something wrong in your own code.

all the best
Matthias

On 03.11.2015 08:20, weikaimas at 163.com wrote:

Hi, 
  
 I have a branch and price algorithm. I am facing a problem when I set the initial solution.

When I set the parameter to zero for each variable in objective function, SCIP shows the primal bound is 30. 

In my problem, the primal bound given by SCIP also 30 unit bigger than the real primal bound.

I don't know why this happens.
I attach the initial model and SCIP result in the following.

\ENCODING=ISO-8859-1
\Problem name: mymodel

Minimize
 obj:
Subject To
 Constraint0:   x_1_1  = 30
 Constraint1:   x_2_1  = 10
 Constraint2:   x_3_1  = 30
 Constraint3:   x_4_1  = 19
 Constraint4:   x_5_1  = 17
 Constraint5:   x_6_1  = 22
 Constraint6:   x_7_1  = 28
 Constraint7:   x_8_1  = 21
 Constraint8:   x_9_1  = 27
 Constraint9:   x_10_1  = 20
 Constraint10:  x_11_1  = 10
 Constraint11:  x_12_1  = 21
 Constraint12:  x_13_1  = 14
 Constraint13:  x_14_1  = 11
 Constraint14:  x_15_1  = 28
 Constraint15:  x_16_1  = 21
 Constraint16:  x_17_1  = 21
 Constraint17:  x_18_1  = 20
 Constraint18:  x_19_1  = 16
 Constraint19:  x_20_1  = 24
 Constraint20:  - RgConstraint20  = 0
 Constraint21:  - RgConstraint21  = 0
 Constraint22:  - RgConstraint22  = 0
 Constraint23:  - RgConstraint23  = 0
 Constraint24:  - RgConstraint24  = 0
 Constraint25:  - RgConstraint25  = 0
 Constraint26:  - RgConstraint26  = 0
 Constraint27:  - RgConstraint27  = 0
 Constraint28:  - RgConstraint28  = 0


best regard,

Kai Wei



_______________________________________________
Scip mailing list
Scip at zib.de
http://listserv.zib.de/mailman/listinfo/scip

-- 
\__________________
Matthias Miltenberger
Zuse Institute Berlin
Takustr. 7, 14195 Berlin
www.zib.de/miltenberger
miltenberger at zib.de
+49 (30) 841 85-245
1 attachments
smime.p7s(6K) download 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.zib.de/pipermail/scip/attachments/20151103/01792220/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: fox(11-03-16-01-35).jpg
Type: image/jpeg
Size: 89766 bytes
Desc: not available
URL: <http://listserv.zib.de/pipermail/scip/attachments/20151103/01792220/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: N_initial_model.lp
Type: application/octet-stream
Size: 24814 bytes
Desc: not available
URL: <http://listserv.zib.de/pipermail/scip/attachments/20151103/01792220/attachment.obj>