On Wed, Aug 12, 2009 at 8:03 AM, M. Backens<m.back...@googlemail.com> wrote: > > I have in fact been working on a units package for Sage this summer, > based on the DimPy package for Python and am now nearing the end of my > project. > > I wasn't expecting to be putting things online for another week or > two, but I've put some preliminary documentation and the current > version of the source code at http://www.inference.phy.cam.ac.uk/dimpy/ > > The package implements > - quantities (as numbers with dimensions attached, where dimensions > are the SI units or self-defined non-physical units) > - many pre-defined units and some physical constants > - user can define new physical and non-physical units > - unit conversions (because of the way quantities are set up, units > are purely a way of printing nicely) > - several different ways of choosing which unit to use (user- > determined, via a look-up register or using a set of base units) > - vectors and matrices containing quantities with different units > - a parser that can handle arithmetic and unit conversions using the > unit symbols (e.g. 'm'), full unit names ('meter') with SI prefixes > ('cm', 'centimeter') and plurals ('meters') > > If I could help in any way, that would be great.
Your tutorial is here, which people reading this should look over: http://www.inference.phy.cam.ac.uk/dimpy/tutorial.html I don't like that in your package everything is converted to floating point: sage: 1/2 * meter/second 0.5 m s^-1 sage: I * meter/second 1.00000000000000*I m s^-1 As a consequence this sort of thing doesn't work: sage: from dimpy import * sage: var('x') x sage: f = x^2 * meter --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /Users/wstein/.sage/temp/flat.local/24833/_Users_wstein__sage_init_sage_0.py in <module>() TypeError: unsupported operand type(s) for *: 'sage.symbolic.expression.Expression' and 'Quantity' And if that worked, then I would like to be able to do sage: f.<any symbolic method> and that is basically impossible with your design. Where does your design for your units package come from? It's dramatically different than what I outlined above. It looks like it is *extremely good* for certain applications in the physical sciences, and could probably easily co-exist with the design I outlined (which is really just a no-brainer clone of mathematica's simple design of units). -- William --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
