Re: [Help-glpk] GLPK on Android

[Joey Rios]

Hi Heinrich,

>
> thank you for your great app.

You're welcome!

>
> I started a stub in the GLPK wikibook:
> https://en.wikibooks.org/wiki/GLPK/Android_app
> Maybe you want to add some more text and a screen shot.

Will take a look soon.

>
> Please, add the text of the GPL v3 license to make it clear how your
> coding can be used.

Where would you recommend it be added?  On the 'help' tab of the app, I discuss the license and allow the user to view the full text of the license.  Are you referring to the source code itself?  I think most of my own java files have included the boiler plate GPL language.

>
> I recognized that you created a wrapper with SWIG. But I could not find
> the SWIG file with which you generated my_wrap.c and glpk_android_wrap.c
> in the github repository. Why did you add both C-files? Which one is used?

My guess is that my_wrap.c is an orphan file from my initial tries to use SWIG.  I'll get rid of it and rebuild to make sure that's the case.  I did this work several months ago and am not a SWIG expert.  Is it the .i file you are referring to?  I looked at my shell history to remember what I did and I saw this:

  309  swig -java -package com.littlepancake.glpk.jni glpk_android.i 

  310  ls *.java

  311  cp *.java ~/Development/glpk_workspace/GLPKLibrary/src/com/littlepancake/glpk/jni/

So I guess the file you'd need to reproduce what I did is the glpk_android.i that I wrote.  Does that sound correct?

>
> In GLPK for Java (http://glpk-java.sf.net) I added some coding to catch
> errors which may occur while calling the native library. I suggest to
> add such error handling also to the app.

I think ultimately, it would be a great step forward to rely on a project such as yours for the jni wrappers.  But when I first looked at that, I was a bit overwhelmed by the code.  I found it easier to build up from the SWIG tutorials.  I'd be happy to find a way to leverage your work on that part of the software.

>
> Is there something that should be changed in GLPK for Java to make it
> more suitable for building your Android app?

I don't think so.  However, I do know that if certain functions are called the app will crash.  I didn't dig to far in since the basic LP solving was working.  As users start to play with the library on Android, I hope they provide reports of how it is working and not working for them.

>
> Allowing to use the GMPL language instead of the LP format in the app
> would be logical next step. In GLPK for Java you will find file
> examples/java/GmplSwing.java which could serve as a starting point.

I'll take a look.  It would be relatively easy to add a tab demonstrating any other format (assuming the library calls don't crash anything!).

>
> Adding some example files and a GMPL cheatsheet would also be helpful.

Happy to take pull requests to the github repo!

Thanks,

Joey

>
> Best regards
>
> Heinrich Schuchardt
>
> On 16.11.2014 20:25, Joey Rios wrote:
> > Hi GLPKers,
> >
> > Just wanted to announce a new app and open source project I've put out
> > there. I've gotten GLPK to compile and run within an Android app. I
> > did this a few months ago and it just sort of languished on my local
> > machine. I've cleaned it up and posted all the source to github and
> > placed the app on the Google Play store.
> >
> > https://play.google.com/store/apps/details?id=com.littlepancake.glpk
> >
> > https://github.com/alotau/GLPKAndroid/tree/master
> >
> > I'd be happy if Android-inclined GLPK folks tried out either just the
> > app or the app and the source code. Any feedback on the app or the
> > source would be appreciated. Even if you just download the app (it's
> > free) and click around, I'd appreciate a review on the Play store to
> > increase the project's visibility.
> >
> > The app isn't too exciting, but it should demonstrate that GLPK is doing
> > something. You can enter a model in Mathprog format and solve it.
> > There isn't too much feedback from the app if there is a problem with
> > the model, but there should be enough there for people who are familiar
> > with Mathprog and GLPK.
> >
> > Anyway, that's it.
> >
> > Thanks,
> > Joey
>
>