digits of Pi

[Richard B. Kreckel]

Dear Paul,

Paul Zimmermann wrote:
>>> with GMP 5.0.0 and MPFR, it is possible to compute 10^9 bits of Pi in less
>>> than one hour on a 2.83Ghz Core 2:
>>>
>>> patate% time ./tconst_pi 1000000000 0 0
>>> Seed GMP_CHECK_RANDOMIZE=1263667646 (include this in bug reports)
>>> 2885.349u 192.229s 52:16.55 98.1%       0+0k 280+16io 3pf+0w
>>>
>>> Paul Zimmermann
>>> _______________________________________________
>>> gmp-discuss mailing list
>>> gmp-discuss at gmplib.org
>>> https://gmplib.org/mailman/listinfo/gmp-discuss
>>>
> 
> of course, but it took much longer to get the result. With GMP 4.3.1:
> 
> patate% time ./tconst_pi.431 1000000000 0 0
> Seed GMP_CHECK_RANDOMIZE=1264027541 (include this in bug reports)
> 5493.252u 131.865s 1:34:17.94 99.4%     0+0k 768+0io 2pf+0w

Using CLN's code (which is binary splitting Chudnovskys' formula) on a 
Core 2 Duo @ 3.0GHz one computes the same number of digits (301029996 
decimal digits, to be precise) in 27m31s (user), 0m34s (sys).

What's interesting is that I see no measureable difference using GMP 
4.3.2 and GMP 5.0.0. This is with CLN-1.3.1 where the bulk of 
multiplication is in mpn_mul, so I do wonder about the reasons for that.

   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>