Linking Cplex in school server

[jshong]

Hi. I have a pretty basic question. 

I wonder how to link Cplex in my school server to yalmip. 

I can open matlab 2013b using Xwin 32. It is a UNIX system.

They said they installed Cplex for me. 

But yalmip doesn't recognize Cplex in my school server. 

Could you tell me at least what I should ask IT staff ?

Thanks. 

-JS

[Johan Löfberg]

The matlab interfaces to cplex supplied by ibm have to visible on MATLABs path, so you need the location of these

Here

 addpath('C:\Program Files\IBM\ILOG\CPLEX_Studio125\cplex\matlab\x64_win64');

[jshong]

Is matlab\x64_win64 folder same in Linux version as well?

 

[Johan Löfberg]

Don't know what the directory structure looks like on linux

[jshong]

Actually, I added the path they told me. 

I checked that ' CPLEX_Studio_Preview1251/cplex/matlab'  is added. 

I typed help cplexlp and checked the message. 

It looks cplex is installed in my school server. 

But, Yalmip can't find cplex. 

Do you have any idea how to fix this? 

Thanks for your help. 

-JS

[Johan Löfberg]

You have to add the directory where cplexlp etc are located

>> which cplexlp

C:\Program Files\IBM\ILOG\CPLEX_Studio125\cplex\matlab\x64_win64\cplexlp.p

My guess is you should have another level in the directory such as x64_lx or something like that

[jshong]

Oh, I didn't write it correctly. Sorry.

Definitely, cplexlp is working for sure. 

>> which cplexlp

/opt/ibm/ILOG/CPLEX_Studio_Preview1251/cplex/matlab/cplexlp.p

 

But there is no folder 'cplex/matlab/x64_win64'.

Do you have any idea why x64_win64 folder doesn't exist?

My guess is that they installed Cplex Studio preview edition and it doesn't have x64_win64. 

What do you think?

[Johan Löfberg]

You just said that the software is installed on a unix server, so why should there be a win64 directory?

[jshong]

Yes. That was a dumb question. 

I am new to Unix system so I didn't know that. 

I think the main problem is they installed preview (trial) version. 

This is probably because my academic license cannot be used in Unix system. 

Is there any way to link trial version of Cplex to yalmip?

Thanks. 

-JS

[Johan Löfberg]

If the MATLAB interfaces to cplex are in the path, YALMIP will use them. Nothing more has to be done from YALMIPs point of view. If your installation doesn't have the MATLAB layer, YALMIP cannot be used.

[Johan Löfberg]

...and academic license is most likely available for unix (they have it for solaris)

However, I don't think they can install that globally, it is intended for your personal computer. Why don't you installl it on your own machine?

[jshong]

I did install academic version in my PC. 

But I want to solve several MIPs at the same time in UNIX system. 

It is weird that Yalmip doesn't recognize Cplex in preview edition. 

Can you link Cplex in preview edition of ILOG?

Is there any other MIP solver I can install in UNIX system?

I asked my IT staff to install the Gurobi but they told me they can't. (They said they need to set license server, which I don't understand)

[Johan Löfberg]

YALMIP does not care about the license. All that matters is that the MATLAB interface is on your path

What do you have in the matlab directory you talk about?

dir('/yourpath/CPLEX_Studio_Preview1251/cplex/matlab'

[Johan Löfberg]

...and I presume you are using the absolutely last version of YALMIP. Old versions do not recognize 12.5.1

[jshong]

Yes. You were right. I installed older version of yalmip in my Unix account. 

I installed new version of yalmip and checked CPLEX 12.5.1 is linked.

But, I found a weird thing.

I tested my MIP problem with small number of variables. It is solved in my PC with Cplex 12.5. 

But matlab in server simply gives NaN solutions. 

I found the same thing occurs in the other problem in yalmip website. 

I run this both in my PC and server. 

x = sdpvar(5,1);

A = ones(15,5);

b = ones(15,1);

obj = sum(x) + sum((x-3).^4); % 4th order objective

ops = sdpsettings('solver','bnb','bnb.solver','fmincon');

solvesdp([A*x <= b, integer(x)],obj,ops)

My PC gives

* Starting YALMIP integer branch & bound.

* Lower solver   : fmincon-standard

* Upper solver   : rounder

* Max iterations : 300

 

Warning : The continuous relaxation may be nonconvex. This means 

that the branching process is not guaranteed to find a

globally optimal solution, since the lower bound can be

invalid. Hence, do not trust the bound or the gap...

 Node       Upper       Gap(%)      Lower    Open

    1 :    4.050E+02    13.55      3.083E+02   2  Successfully solved 

    2 :    4.050E+02    13.55      3.083E+02   3  Successfully solved 

    3 :    3.410E+02     4.64      3.108E+02   2  Successfully solved 

    4 :    3.410E+02     4.64      3.108E+02   3  Successfully solved 

    5 :    3.410E+02     4.01      3.147E+02   2  Successfully solved 

    6 :    3.410E+02     4.01      3.147E+02   3  Successfully solved 

    7 :    3.410E+02     2.85      3.221E+02   2  Successfully solved 

    8 :    3.410E+02     2.85      3.221E+02   1  Successfully solved 

    9 :    3.410E+02     2.85      3.221E+02   0  Successfully solved 

+   9 Finishing.  Cost: 341

ans = 

    yalmiptime: 0.0440

    solvertime: 0.2700

          info: 'Successfully solved (BNB)'

       problem: 0

>> double(x)

ans =

     0

     0

     0

     1

     0

But server gives

IBM ILOG CPLEX Optimization Studio Preview Edition good for 86 more days.

* Starting YALMIP integer branch & bound.

* Lower solver   : fmincon-standard

* Upper solver   : rounder

* Max iterations : 300

 

Warning : The continuous relaxation may be nonconvex. This means 

that the branching process is not guaranteed to find a

globally optimal solution, since the lower bound can be

invalid. Hence, do not trust the bound or the gap...

 Node       Upper       Gap(%)      Lower    Open

ans = 

    yalmiptime: NaN

    solvertime: NaN

          info: [1x135 char]

       problem: 9

>> double(x)

ans =

   NaN

   NaN

   NaN

   NaN

   NaN

Do you have any idea why this happens?

Thanks. 

-JS

[Johan Löfberg]

You are solving a nonlinear integer program using the built-in framework bnb with fmincon as local solver, so this has nothing to do with cplex.

fmincon most likely crashed on your server. To see the full crash, use

ops = sdpsettings('solver','bnb','bnb.solver','fmincon','debug',1);

[Johan Löfberg]

and when you solved the MILP, what was displayed when you ran solvesdp? What was the error code? Was it 9 (Unknown problem in solver) as in the crash above? Turn on the debug flag and report the complete display and error codes etc

[jshong]

I run my code for MIP and got this.

CPLEX Error  1016: Restricted version.  Problem size limits exceeded.

This is too bad.

When I run this in my PC. It says

Optimize a model with 28882 rows, 4806 columns and 82058 nonzeros

Found heuristic solution: objective 6628.81

Presolve removed 7402 rows and 1301 columns

Presolve time: 0.24s

Presolved: 21480 rows, 3505 columns, 72060 nonzeros

Variable types: 3005 continuous, 500 integer (500 binary)

Is there any other solver which can be used to solve my problem in school server?

I requested Gurobi to be installed but IT staff told me they couldn't.

Thanks. 

-JS

[Johan Löfberg]

I don't think any of the academic licenses for the commercial solvers (cplex, gurobi,mosek and xpress) can be installed on a server. If you want one of those, you will have to run it on your own machine (I am not sure though, but that is my guess)

Here are the integer solvers supported by YALMIP

http://users.isy.liu.se/johanl/yalmip/pmwiki.php?n=Category.IntegerProgrammingSolver

[jshong]

Thanks, Johan. 

It's too bad that academic licenses cannot be installed on a school server. 

I will try non-commercial server. 

Anyway, I really appreciate your help. 

-JS

[convex_optimization]

i have the same problem. i downloaded the recent version of yalmip, i have cplex 12.5, added the path but yalmip cannot find the cplex.
when i write which cplexlp, i get:

C:\IBM\ILOG\CPLEX_Studio125\cplex\matlab\x86_win32\cplexlp.p

This is how setpath looks like:

[Johan Löfberg]

YALMIP looks for the file cplexlink125 (on windows 64bit cplexlink125.mexw64)

[convex_optimization]

so, is the cause of error  i should have 64 bit cplex?

[Johan Löfberg]

We don't know which computer you have. mexext tells you which file ending your binary has, and on a windows systems it would be placed in a directory such as C:\Program Files\IBM\ILOG\CPLEX_Studio1261\cplex\matlab\x64_win64\

[Johan Löfberg]

from your path it appears you've installed a 32 bit version. I highly doubt you have a 32 bit installation in the year 2016...