hi cosmo-torun,

This follows from a conversation some of us had recently. Debian stable (etch) includes GMP and MPFR - i ran a test program which quite nicely does e.g. 200-bit floating point operations, including trig functions, and gets reasonable answers. :)

Source + doc: http://gmplib.org/ http://www.mpfr.org/

These are both under the LGPL instead of the GPL, so it turns out that... the non-free program Mathematica uses the free program GMP ! So apparently non-free software libraries are not good enough for Mathematica for this purpose. Or Mathematica is just "abusing the commons". [the commons: http://en.wikipedia.org/wiki/The_commons ]

pozdr boud

On Wed, 14 Jan 2009, Bartosz Lew wrote:

...

...

But within standard types long double is better than double etc.

i assume this means you've experimented with this? Based on the wikipedia entries, i suggested to Zbyszek that this could be interesting, but i haven't tried it. My understanding is that it pushes to the limit of the machine you're using, which can be better than 64bit, but is nowhere near 128bit. :)

mmm, don't remember which means that probably not much.

But, I never experienced a need for such extremely super-duper high accuracy. As far as the calculation is actually correct within the given precision it's cool. Eg. CMBFast works in 4byte float numbers and it's sufficient. AFAIK people still very often use 4byte floats. My opinion is that is the code returns wrong numbers its an indication that it should be rewritten in smarter way rather than going to long doubles or quadruple precisions.

...

Tomorrow Thursday i've got linux@IF so i'm very unlikely to be at KRA. But that's not an argument against both of you coming here and doing stuff. :)

ok.

B.