On Thu, Nov 17, 2022 at 5:29 PM Scott Ransom <sran...@nrao.edu> wrote:
> A quick response from one of the leaders of a team that requires 80bit > extended precision for > astronomical work... > > "extended precision is pretty useless" unless you need it. And the > high-precision pulsar timing > community needs it. Standard double precision (64-bit) values do not > contain enough precision for us > to pass relative astronomical times via a single float without extended > precision (the precision > ends up being at the ~1 microsec level over decades of time differences, > and we need it at the > ~1-10ns level) nor can we store the measured spin frequencies (or do > calculations on them) of our > millisecond pulsars with enough precision. Those spin frequencies can have > 16-17 digits of base-10 > precision (i.e. we measure them to that precision). This is why we use > 80-bit floats (usually via > Linux, but also on non X1 Mac hardware if you use the correct compilers) > extensively. > > Numpy is a key component of the PINT software to do high-precision pulsar > timing, and we use it > partly *because* it has long double support (with 80-bit extended > precision): > https://github.com/nanograv/PINT > And see the published paper here, particularly Sec 3.3.1 and footnote #42: > https://ui.adsabs.harvard.edu/abs/2021ApJ...911...45L/abstract > > Going to software quad precision would certainly work, but it would > definitely make things much > slower for our matrix and vector math. > > We would definitely love to see a solution for this that allows us to get > the extra precision we > need on other platforms besides Intel/AMD64+Linux (primarily), but giving > up extended precision on > those platforms would *definitely* hurt. I can tell you that the pulsar > community would definitely > be against option "B". And I suspect that there are other users out there > as well. > Hi Scott, Thanks for sharing your feedback! Would you or some of your colleagues be open to helping maintain a library that adds the 80-bit extended precision dtype into NumPy? This would be a variation of Ralf's "option A." Best, Stephan > > Scott > NANOGrav Chair > www.nanograv.org > > > -- > Scott M. Ransom Address: NRAO > Phone: (434) 296-0320 520 Edgemont Rd. > email: sran...@nrao.edu Charlottesville, VA 22903 USA > GPG Fingerprint: A40A 94F2 3F48 4136 3AC4 9598 92D5 25CB 22A6 7B65 > _______________________________________________ > NumPy-Discussion mailing list -- numpy-discussion@python.org > To unsubscribe send an email to numpy-discussion-le...@python.org > https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ > Member address: sho...@gmail.com >
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