ECL? was ..Re: Runtime determination of share directories?

Michael Abshoff wrote:
> Raymond Toy wrote:
>   
>> I didn't find it that easy to build MPFR and/or GMP.
>>     
>
> Ok, I personally have zero problems with GMP and MPFR while getting 
> various lisps to compile did cost me considerable more effort. And gcc 
> 4.2.x recommends GMP and MPFR while 4.3.x and later require it for 
>   
Yes, I had to build mpfr and gmp because gcc wanted them.  It took a
while to get it built.  (I don't normally do this unless I have to.  I
thought I needed a recent gcc on solaris/sparc.)  So now I actually have
them available.
> constant folding. So any system providing recent gcc should have them 
> available. Ecl has its own GMP copy in tree and so do other lisp 
> implementations.
>
>   
>> But Maxima can't run without a lisp, but it does run well (quite well,
>> IMNSHO) without MPFR/GMP. :-)
>>     
>
> Absolutely, but given the periodically reappearing discussion about 
> easier use of external libraries written in C/C++/Fortran something 
> worthwhile to think about IMHO would be MPFR. Since I am not doing any 
> of the work this is merely a suggestion.
>   
The best part of using an ffi is having my lisp die because I called the
foreign function incorrectly.  Or it decided an error happened and
exiting is the best way.  :-)

(But I do use FFI for stuff, as needed.)

>> Do you have such an example?  I'd really like to see it, since I
>>     
>
> I need to dig it out of the Sage bug tracker and that will take some time.
>   
I would certainly like it, but if it's too much work, that's ok.
>
>
> AFAIK the advantage if qd is that it sets rounding mode to 53 bits and 
> hence does not rely on 80 bit representation. There is a well known 
> paper that shows that compilers optimizing expression trees will cause 
> precision loss. But qd at least to my understanding should not be 
> affected by this issue.
>
>   
Setting the rounding mode to 53 bits isn't actually enough.  I saw some
Java numerics slide that explained this.  Even though the precision was
53 bits, the exponent is still 16 bits, so numbers don't
underflow/overflow as you would expect for double precision.  The slides
explained how to solve this problem, but it added a factor of 2-4 in
execution or something like that.

Ray