William Stein wrote: > On Tue, Aug 11, 2009 at 11:30 PM, Jason > Grout<jason-s...@creativetrax.com> wrote: >> William Stein wrote: >>> Hi, >>> >>> I just wanted to let people know that David Ackerman -- a UW student who >>> took my course on Sage last quarter -- is working (funded by NSF) on >>> creating a "units package" for Sage right _now_. If anybody has any >>> pseudo-sage code that involves units that they wished work, please post >>> it to this thread. What do you want units to *do*? >>> >> Is he doing something from scratch or is he working from the packages >> that have come up from time to time here? > > He is doing something from scratch. > > I had planned to have him work on integrating some existing package, > but after evaluating that approach he said it didn't seem to make > sense (at least he has a lot of experience using Sage, since he took > my class). I didn't have an opinion one way or the other, but we > decided to ask -- "what is a so called units package supposed to do > anyways" since I honestly couldn't really tell you. I would use one > to convert between Fahrenheit and Celcius, and maybe dollars and euros > :-). We google around and found that Matlab didn't seem to come with > a units package, but there were several third party packages -- anyway > Sage isn't much like Matlab so looking there seemed pointless. Then > we looked at Mathematica's included units package and read all the > documentation and examples of it. That was enlightening, and > suggested doing almost precisely what Robert Dodier keeps telling us > to do, which is make the different units just be symbolic variables, > plus have some extra table somewhere of conversions (where everything > is kept as exact fractions), and add a few functions to do > conversions. If you read the Mathematica docs you'll see that *all* > their units package is is: > > * a function Convert to convert between units > > * a very big list of different standard units (e.g., Foot, > Mile, Meter Second, etc.), which are all literally just symbolic > variables. > > * ConvertTemperature (and 3 other convert style functions). > > That's it.
I would also hope that there is a way to define my own units in terms of standard units, or even my own system. For example, 100 pages is a book, 10 books is a shelf, 14 shelves is a bookcase, etc. Thanks, Jason --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
