Re: [sage-devel] Re: Issue With Implementation of Gamma Function

2014-02-17 Thread Zimmermann Paul
Hi Jori, > Date: Mon, 17 Feb 2014 14:56:56 +0200 (EET) > From: Jori Mantysalo >=20 > On Mon, 17 Feb 2014, Zimmermann Paul wrote: >=20 > > On my computer, computing gamma(Pi^2) to 1 bits takes about 1.4s (f= or the > > first computation, when Bernoulli numb

Re: [sage-devel] Re: Issue With Implementation of Gamma Function

2014-02-17 Thread Zimmermann Paul
a last update: MPFR now uses the Von Staudt=E2=80=93Clausen theorem to comp= ute Bernoulli numbers (thanks to Fredrik Johansson for pointing out this formul= a). On my computer, computing gamma(Pi^2) to 1 bits takes about 1.4s (for t= he first computation, when Bernoulli numbers are not cached)

Re: [sage-devel] Re: Issue With Implementation of Gamma Function

2014-02-13 Thread Zimmermann Paul
an update on this: we now cache Bernoulli numbers in MPFR, and the time to compute 1000 times gamma(pi^2) at precision 1000 bits has decreased to 0.4s on my computer (was 2.9s before). In comparison, Pari/GP (which also does cache Bernoulli numbers) takes 0.5s. Best regards, Paul Zimmermann -- Y

Re: [sage-devel] Re: Issue With Implementation of Gamma Function

2014-02-12 Thread Zimmermann Paul
Dear Jori, > And reason is of course clear, as Fredrik Johansson wrote "If you cache > Bernoulli numbers, - -". in fact there is another reason: the MPFR code computes the Bernoulli numbers exactly, as integers B(2n)*(2n+1)!, whereas Pari/GP computes a floating-point approximation. For 10

Re: [sage-devel] Re: Issue With Implementation of Gamma Function

2014-02-12 Thread Zimmermann Paul
William, thank you for putting me in cc. > From: William Stein > Date: Wed, 12 Feb 2014 06:01:29 -0800 > > On Wed, Feb 12, 2014 at 4:55 AM, wrote: > > Ah, I see what you mean. If that's the case then I understand. How does > > one find out if this is true? > > 1. It is *NOT* true.

[sage-devel] Re: real literals and IEEE-754

2014-01-06 Thread Zimmermann Paul
Nils, > Date: Mon, 6 Jan 2014 13:18:07 -0800 (PST) > From: Nils Bruin > > On Monday, January 6, 2014 12:46:19 PM UTC-8, Zimmermann Paul wrote: > > > What about getting rid of real literals? > > > > I think they exist mainly to let > > RealF

[sage-devel] real literals and IEEE-754

2014-01-06 Thread Zimmermann Paul
Hi, [since I am not subscribed to sage-devel, please keep me in cc] the concept of real literals, which was intended (as far as I understand) to keep exactly track of inputs like "1e-20", leads to the following: sage: a=RealField(53)(1e-20) sage: Reals(200)(a) 1.00

Re: [sage-devel] imag(CC(infinity)) is 0?

2013-10-07 Thread Zimmermann Paul
Peter, > I think a case could be made for having two versions of the current RR: one > like the current one (more like a model of the extended real line) and one > where overflow or division by zero raises an exception instead of returning > +/- infinity (more like a model of the usual r

Re: [sage-devel] imag(CC(infinity)) is 0?

2013-10-04 Thread Zimmermann Paul
William, [please forward to sage-devel since I'm not sure I'm allowed to post there] > The implementation of RR and CC in Sage are a very direct wrapping of > MPFR, which is the most well-thought out efficient implementation of > floating point real numbers I've ever seen. It is worth vis

[sage-devel] Re: Build Error in gf2x package on AMD Athlon XP 2600+

2013-09-23 Thread Zimmermann Paul
Jean-Pierre, [please forward to sage-devel, since I'm not subscribed, thus my mail will be rejected] thank you for forwarding us that message: > Date: Fri, 20 Sep 2013 11:36:26 -0700 (PDT) > From: Jean-Pierre Flori > Cc: Zimmermann Paul > > [1:multipart/alternati

[sage-devel] Annoying inconsistency of type in doctests

2013-04-19 Thread Zimmermann Paul
this is now ticket http://trac.sagemath.org/sage_trac/ticket/14466 Paul -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. T