Stuff with sets: In [1]: squares = TransformationSet(Lambda(x, x**2), S.Naturals)
In [2]: squares Out[2]: ⎧ 2 ⎫ ⎨x | x ∊ ℕ⎬ ⎩ ⎭ On Wed, Jul 24, 2013 at 8:48 AM, Matthew Rocklin <[email protected]> wrote: > SymPy can represent sets easily. We do not have a standard class to > couple sets to variables but it might be useful. I had to deal with this > problem when making sympy.stats. Unfortunately I can't recommend the final > implementation. I'd love to have something cleaner within core sympy. I > think a first draft might be as simple as a pairing of variables with sets. > > > On Wed, Jul 24, 2013 at 6:34 AM, Stefan Krastanov < > [email protected]> wrote: > >> It depends what exactly you want to do. >> >> If you need it just for typography purposes (e.g. writing something in >> IPython notebook and wanting to print the expression) you are using sympy >> incorrectly. SymPy is not a typography library. (if you insists there are >> hacks to do it) >> >> On the other hand quite frequently you need this for meaningful >> mathematics. >> >> - if you want to work on polynomials and do certain operations (finding >> roots, etc) over a given field, you do this by specifying the field during >> the creation of the polynomial. >> >> - there is some work in progress to be able to do the same for matrices, >> but it is not ready. >> >> - in general, there is the assumption module. It is a bit of a mess, >> because we have an old and a new assumption module and we try to move to >> the new one. If all that you want is for abs(x) to automatically return x >> (or something similar) it suffices to define x as `x=Symbol('x', >> positive=True)`. There are a few other handles like `real` and `integer`. >> >> - if you need something more general or more fancy, we may have it in >> some (possibly unfinished, mostly unused) form, but it goes deeper in SymPy >> so a more precise question will help us give you a more precise answer. >> >> >> On 24 July 2013 13:10, Ben Lucato <[email protected]> wrote: >> >>> We can represent domains on paper quite easily - for instance we can >>> write x < 0, or alternatively x (epsilon symbol) R-, or even x (epsilon >>> symbol) (-infinity, 0) >>> >>> I looked around but couldn't really find that - is there a canonical way >>> to be writing domains in SymPy? >>> >>> -- >>> 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 http://groups.google.com/group/sympy. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >>> >>> >> >> -- >> 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 http://groups.google.com/group/sympy. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- 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 http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
