Ideally we'd like units to be used seamlessly everywhere. Unfortunately there's still a bit of work to do to reach that level.
On Friday, 3 March 2017 12:04:56 UTC+1, [email protected] wrote: > > I was hoping so, but apparently unitsystems.Quantity currently only allows > numerical computations, not symbolic ones. > > At least, when I try > > >>> x = Quantity(factor=Symbol("x")) > > I get a NotImplementedError (see also code at > http://docs.sympy.org/dev/_modules/sympy/physics/unitsystems/quantities.html > ). > > I interpret this to mean that hopefully support for symbolic physical > quantities is planned, but I'd like to get an idea of when it might be > available... > > Am Donnerstag, 2. März 2017 19:24:10 UTC+1 schrieb Aaron Meurer: >> >> I believe the sympy.physics.unitsystems module is capable of doing >> this. http://docs.sympy.org/latest/modules/physics/unitsystems/index.html >> >> Aaron Meurer >> >> On Thu, Mar 2, 2017 at 4:56 AM, <[email protected]> wrote: >> > I wonder whether it is currently (or will soon be) possible to specify >> which >> > physical dimension (or unit) a symbol has and have sympy check that >> these >> > are compatible when, say, adding symbols or expressions, and compute >> the >> > resulting dimension (or unit) when, say, multiplying symbols or >> expressions? >> > >> > I imagine something like >> > >> > >> >>>> x = Symbol("x", dimension=length/time) >> >>>> y = Symbol("y", dimension=time) >> >>>> x + y >> > DimensionError: incompatible dimensions cannot be added >> >>>> (x * y).dimension >> > length >> > >> > >> > I know that sympy has now units, but it seems they are only used in >> > numerical computations, not in symbolic ones, am I right? >> > >> > If the imagined functionality is not present or planned to be added >> soon, >> > how would you advise me to add it for my project by subclassing? Would >> it be >> > sufficient to subclass sympy.Expr or would I have to subclass Add, Mul, >> etc. >> > as well? >> > >> > Thanks, Jobst >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups >> > "sympy" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an >> > email to [email protected]. >> > To post to this group, send email to [email protected]. >> > Visit this group at https://groups.google.com/group/sympy. >> > To view this discussion on the web visit >> > >> https://groups.google.com/d/msgid/sympy/1ce09588-af7d-4781-9ce9-cac5cf858086%40googlegroups.com. >> >> >> > For more options, visit https://groups.google.com/d/optout. >> > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/0712b4e5-e7d5-43f5-b3f6-602aea647ea7%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
