[gecode-users] Gecode 4.0.0

[Filip Konvička]

All,

Thanks for the update.  This all sounds very good to me.

Vincent, I haven't experimented much with low-level libraries for 
rounding and controlling the FPU on Windows.  But I'd say if there are 
issues with the trigonometric functions then just don't include them in 
the first release.  Once more people can get their hands on this it 
could be you get the solution for free :-)

I was looking into smath some time ago but I think this is not much 
portable (and probably not maintained anymore).  And the subject is so 
tricky that I think it is not a good idea to start some new 
implementation.  I think it's better to have a configuration option to 
include any library available and supported by Boost.Interval, and as a 
consequence enabling/disabling some constraints implementations in 
Gecode based on the capabilities.  The point is, some people (like me) 
may not need Trigonometric and Transcendental functions at all...  But 
this is also for Christian to decide whether this approach is acceptable 
(sometimes having a constraint available and sometimes not).

Best Regards,
Filip

> Hi Vincent,
>
> 2011/11/4 Vincent Barichard <Vincent.Barichard at univ-angers.fr 
> <mailto:Vincent.Barichard at univ-angers.fr>>
>
>     e about the rounding for trigonometric and transcendental
>     functions. Indeed, boost doesn't provide full rounding functions
>     for trigonometric and transcendental functions. To achieve correct
>     rounding, it relies on other libraries like MPFR. If I can't rely
>     on standard C maths functions to get a correct rounding, I have to
>     investigate on other alternatives. MPFR is not a good choice for
>     Windows users, so maybe another library (CRLibm ? others ?).
>
>
> I think that if you have something like cygwin or mingw you can 
> install MPFR in an easy way. The nice think about that library is that 
> is very well tested and brings support for different architectures. 
> GCC uses it and this is a good sign (?). I don't know if the library 
> can be distributed with gecode or at least statically linked in the 
> future libgecodefloat. I don't know too much about windows, tough.
>
>     I'd appreciate any advice on this. Does someone known a good
>     "light" maths library which gives exact rounding ?
>
>     If you have any questions or remarks, don't hesitate to contact me!
>
>
> It will be nice if you can get some ideas from smathlib:
> http://interval.sourceforge.net/interval/C/smathlib/README.html
>
> this library was developed by Timothy Hickey but is pure C and I am 
> not very sure about its portability. It provides its own rounding 
> methods without relying in something else.
>
> Another good library that perform constraint programming 
> on continuous domains is:
>
> http://sourceforge.net/projects/elisa/
>
> But I think you already had a look at that one. It provides nice 
> interval arithmetic constraint that make use of the Newton method to 
> offer better pruning.
>
> Regards,
> -- 
> Gustavo Gutierrez

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