From boud w astro.uni.torun.pl Tue Feb 3 16:37:23 2009 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Tue, 3 Feb 2009 16:37:23 +0100 (CET) Subject: [Cosmo-torun] 200-bit precision floating point arithmetic and trigonometry? In-Reply-To: <200901141535.15335.blew@student.umk.pl> References: <200901141508.32602.blew@student.umk.pl> <200901141535.15335.blew@student.umk.pl> Message-ID: 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 w 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. > From boud w astro.uni.torun.pl Fri Feb 20 16:20:40 2009 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Fri, 20 Feb 2009 16:20:40 +0100 (CET) Subject: [Cosmo-torun] cosmo workshop wt 14:00 27.01.09 B Roukema: 'a hint towards Poincare gravity?' In-Reply-To: References: Message-ID: witam cosmo-torun On Mon, 26 Jan 2009, Boud Roukema wrote: > witam, > > Cosmo workshop tomorrow wtorek 27.01.09 at 14:00 @KRA. > > Boud will talk about his present project: > > 'a hint towards Poincare gravity?' Done. seminar done + article submitted: http://arxiv.org/abs/0902.3402v2 > Everyone is welcome, but be warned: this is a research level work > session, most likely in English. During the next few weeks we will have to see how many (if any) undergrad students are interested in wyklad/seminarium and at what knowledge/research level they are (new to cosmo or already done a basic course) and sort out days/times. Based on what is officially on usosweb, i propose we start with: Fri 27.02.09 - 16.00 godz workshop - Agnieszka (to be confirmed). Agnieszka, you said today, if i understood correctly, that you can confirm during the next few days or so. Please just reply to the public list once you have confirmation either way. :) The idea of the talk is very much workshop-ish, describing the scientific aims and where you've got to so far and also where you haven't got to and also where people might be able to help with specific bottlenecks in your research. Zbyszek - is Friday at 16.00 okay for you? Again, please reply to the public list. Bartek - i think you said that Fri @16.00 should be OK. Hopefully we should have all 3 doktoranci + me together for this workshop, and maybe also some undergrads... And then get into a cycle of a workshop type cosmo research presentation nearly every week... :) pozdr boud From szachula w astro.uni.torun.pl Tue Feb 24 13:11:41 2009 From: szachula w astro.uni.torun.pl (Agnieszka Szaniewska) Date: Tue, 24 Feb 2009 13:11:41 +0100 (CET) Subject: [Cosmo-torun] cosmo workshop wt 14:00 27.01.09 B Roukema: 'a hint towards Poincare gravity?' In-Reply-To: References: Message-ID: Hi everyone, > On Mon, 26 Jan 2009, Boud Roukema wrote: > > During the next few weeks we will have to see how many (if any) > undergrad students are interested in wyklad/seminarium and at what > knowledge/research level they are (new to cosmo or already done a basic course) > and sort out days/times. Based on what is officially on usosweb, > i propose we start with: > > Fri 27.02.09 - 16.00 godz workshop - Agnieszka (to be confirmed). > > Agnieszka, you said today, if i understood correctly, that you can > confirm during the next few days or so. Please just reply to the > public list once you have confirmation either way. :) The idea of the > talk is very much workshop-ish, describing the scientific aims and > where you've got to so far and also where you haven't got to and > also where people might be able to help with specific bottlenecks > in your research. > I'm not sure if I can come on Friday. I'll confirm/not confirm tomorrow evening. I don't know when I have consultations with the students. Pozdr, Agnieszka From boud w astro.uni.torun.pl Tue Feb 24 15:21:50 2009 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Tue, 24 Feb 2009 15:21:50 +0100 (CET) Subject: [Cosmo-torun] cosmo workshop piatek 14:00 27.02.09 TBC (to be confirmed) In-Reply-To: References: Message-ID: hi Agnieszka, On Tue, 24 Feb 2009, Agnieszka Szaniewska wrote: >> Fri 27.02.09 - 16.00 godz workshop - Agnieszka (to be confirmed). > I'm not sure if I can come on Friday. I'll confirm/not confirm tomorrow > evening. I don't know when I have consultations with the students. i have a problem with 16.00godz Friday, so i propose 14.00 godz Friday, awaiting your confirmation/cancellation. pozdr boud From szachula w astro.uni.torun.pl Wed Feb 25 16:49:20 2009 From: szachula w astro.uni.torun.pl (Agnieszka Szaniewska) Date: Wed, 25 Feb 2009 16:49:20 +0100 (CET) Subject: [Cosmo-torun] cosmo workshop piatek 14:00 27.02.09 TBC (to be confirmed) In-Reply-To: References: Message-ID: Hi everyone, On Tue, 24 Feb 2009, Boud Roukema wrote: > hi Agnieszka, > > i have a problem with 16.00godz Friday, so i propose 14.00 godz Friday, > awaiting your confirmation/cancellation. > Friday 2 p.m. is ok for me. Pozdr, Agnieszka From boud w astro.uni.torun.pl Wed Feb 25 17:56:25 2009 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Wed, 25 Feb 2009 17:56:25 +0100 (CET) Subject: [Cosmo-torun] cosmo workshop piatek 14:00 27.02.09 @KRA: Agnieszka Szaniewska on Light Dark Matter In-Reply-To: References: Message-ID: witam On Wed, 25 Feb 2009, Agnieszka Szaniewska wrote: > > Hi everyone, > > On Tue, 24 Feb 2009, Boud Roukema wrote: > >> hi Agnieszka, >> >> i have a problem with 16.00godz Friday, so i propose 14.00 godz Friday, >> awaiting your confirmation/cancellation. >> > Friday 2 p.m. is ok for me. > Pozdr, > Agnieszka Great! :) Zbyszek, Bartek, and maybe some others too, hope to see you on Friday. :) There's even a wikipedia entry on LDM now, though it mostly talks about the particle physics motivations and just barely mentions the INTEGRAL/SPI detection: http://en.wikipedia.org/wiki/Light_Dark_Matter pozdr boud From boud w astro.uni.torun.pl Fri Feb 27 15:28:14 2009 From: boud w astro.uni.torun.pl (Boud Roukema) Date: Fri, 27 Feb 2009 15:28:14 +0100 (CET) Subject: [Cosmo-torun] some notes after today's talk - LDM Message-ID: witam cosmo-torun * circular polarisation from synchrotron processes? Kennett & Melrose, 1998, PASA, 15, 211 http://www.atnf.csiro.au/pasa/15_2/kennett/paper/node3.html > In some sources it may be that the relativistic > particles are electron-positron pairs (e.g., Wilson & > Weiler 1997). Electrons and positrons contribute with > the same sign to the linearly polarized component and > with the opposite sign to the circularly polarized > component. If the distributions of electrons and > positrons are the same the wave modes can have no > circular component and, more importantly, the intrinsic > circular polarization from the synchrotron radiation > sums to zero. So if we have different distributions of electrons and positrons, then we get a circular polarisation component. i'm sure there must be more basic texts on this subject... pozdr boud