Re: [Help-glpk] GLPK on 64 bit Linux

[Chris Wolf]

Paul,

I built GLPK  and the JNI wrapper on MacOS with 64 bit switches (-arch x86_64) 
and tested on a 64 bit VM,
however this was on a Mac Book Pro, which has "Intel Core 2 Duo", which are 64 
bit CPUs, but I'm not sure
if the memory bus is 64 bit; if that matters for the purpose of the test.  It 
passed the "make check".

If you have a test-case, I can try it on my build.

Regards,

Chris Wolf


On 3/25/10 8:56 AM, Hammond, Paul wrote:
> Hi,
> 
>  
> 
> I #8217;m including bug-glpk here as this
> is potentially a bug, but it could be something we are doing wrong.
> 
>  
> 
> We are using GLPK with Java (glpk-java-1.0.5),
> but to date have been using it in a 32 bit Linux environment and it #8217;s
> been fine (apart from crashes which we put down to the fact it #8217;s not
> thread safe)
> 
>  
> 
> Now we are trying to use it in a 64 bit
> Linux environment and encountering some strange issues and I #8217;m just
> wondering if anybody else has encountered these and how we might solve it.
> 
>  
> 
> To move to 64 bit, we recompiled the C code
> on 64 bit to produce a new shared object linked to it. It runs and executes no
> problem. For most of our inputs, it gives the same outputs as before, save for
> some very small diffs which I put down to the different floating point
> rounding.
> 
>  
> 
> However, there are cases where a few of the
> numbers differ by amounts that cannot be put down to rounding. We have
> sometimes a fraction like .8xxx going to 0, or we have large numbers differing
> by 10-15%. Again, this is only in very few of the output variables out of 
> quite
> a lot (all the others match fine) and many sets of inputs have no problem but
> it #8217;s enough to pose an issue if it goes wrong for even some of our
> inputs.
> 
>  
> 
> We have dumped the inputs to a .dat file to
> confirm the inputs are the same going in for both 32 bit and 64 bit. It 
> #8217;s
> the same Java software calling the solver so this should be the case.
> 
>  
> 
> Does anybody know about such issues with 64
> bit and the cause? Is there some particular compile flags or switches we need
> to use? Is there anywhere on the net a confirmed working binary version of 
> GLPK
> for Java on 64 bit?
> 
>  
> 
> If this is completely new and you would
> like to investigate, what would you need to be supplied with as a test case to
> look into the problem?
> 
>  
> 
> Thanks,
> 
>  
> 
> Paul
> 
>  
> 
>  
> 
> 
> 
> 
> 
> 
> 
> 
> 
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