solvers not available

[joecheriross]

Hi,

I installed Yaposib 0.3.2. When I executed yaposib.Problem("Clp") it says 'Unknown solver'.
I tried yaposib.avaialable_solvers(). It is listing no solvers.
Please help.

Thanks,
Joe

[tkralphs]

I can try to help, but you'll have to give a bit more information. How did you install yaposib? Did you install Clp? Can you successfully use Clp as a stand-alone solver? What platform are you on? It's possible you are not setting an environment variable yaposib needs to find the Clp library.

[joecheriross]

Sorry for the delay in replying. I missed your response. Saw it today only. I will get back to you with details soon. I will have to redo it again and see. Thanks a lot.

Thanks,
Joe

[sschnug]

In my case, clp is working and marked as available (install from git; ubuntu-based dist), but i can't get cbc to work.

1. How would i achieve to use cbc? Because i already used cylp, i installed cbc from source and linking and usage within cylp is working. But no success with yaposib yet.

2. What exactly is happening when i run the hamiltionian or sat examples? I changed the code to make sure "lp.solveMIP()" is called' and it seems to work and outputs a result (and stdout mentions an integer solution). Is cbc used after all (while not in "available_solvers()")? Or is there some generic branch-and-bound used?

   EDIT: it looks like there is a generic branch-and-bound implementation in clp. I think this is used in my case. Explicitly calling solver=CBC won't work as expected.

Sascha

[chmduquesne]

Hi,

Yaposib only detect solvers if the COIN-OSI library it has been compiled
against also supports these solvers.

In other terms, you need to first make sure that you compile COIN-OSI with
the right options first. To check wich solvers are supported by your
COIN-OSI installation, you will have to write a program including the
headers of the solvers you are interested in, and see if it compiles. I am
afraid I don't know an easier method...

Cheers,
Tof

On Fri, Feb 5, 2016 at 10:43 PM, sschnug notifications@github.com wrote:

In my case, clp is working and marked as available (install from git;
ubuntu-based dist), but i can't get cbc to work.

1. How would i achieve to use cbc? Because i already used cylp, i
   installed cbc from source and linking and usage within cylp is
   working. But no success with yaposib yet.
2. What exactly is happening when i run the hamiltionian or sat
   examples? I changed the code to make sure "lp.solveMIP()" is called' and it
   seems to work and outputs a result (and stdout mentions an integer
   solution). Is cbc used after all (while not in
   "available_solvers()")? Or is there some generic branch-and-bound used?

Sascha

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#3 (comment).

[tkralphs]

@sschnug To follow up on @chmduquesne comment, you need to have a library called libOsiCbc.so.* in one of the system library directories. On Ubuntu, it looks like the package you would need is coin-or-libcbc3.