On Tue, May 22, 2018 at 7:08 AM, Nikhil Pappu <nkhlpa...@gmail.com> wrote: > Ondrej, > > Thanks for the detailed explanation. I get the significance of an AST now. > I will continue with what I am doing now as you mentioned. I will see if I > can make the switch once you send that PR. > If not possible now, then I will definitely work on switching to it later. > I also plan on writing extensive test cases. > > Regarding my status: > I will soon be done with the mathematical entities. I will start with the > symbolic dynamics parts right after that. > > There were some issues I faced : > > 1. Some output results differ between Autolev and SymPy. > For example: > > e = 4*x**2 + 7*x*y + 21*x + 4*y**2 + 21*y > factor(e, x) in Autolev > e.factor(x) in SymPy > > outputs: > > 21*y + 4*y^2 + 4*x*(5.25 + x +1.75*y) > in Autolev > and > > (7*y + 21)*x + 4*x**2 + 4*y**2 + 21*y > in SymPy > > Do differences like these matter? Is there a way to get the same result in > this case? > Should we try to get the exact same outputs in cases like these? > I am in the mindset that end numerical results are more important than > equivalence of intermediate expressions.
It looks like Autolev uses a different definition of factor() than SymPy. I wouldn't in general expect Autolev and SymPy functions to do the same thing just because they have the same name. Autolev's factor() looks more like SymPy's horner(), although I would need to see more examples of what it does to be sure of that. > > 2. One major issue I was facing was with dynamicsymbols. > The thing is I need to define all the Autolev variables as dynamicsymbols > and constants as symbols. > I need to do this because Autolev simply uses Variables and Constants for > everything and I need the variables to be defined as > dynamicsymbols for them to work with the physical entities. > Although the dynamicsymbols would work like they should with the physics > entities, that doesn't seem to be the case with the > mathematical entities of SymPy as they do not seem to be written with > dynamicsymbols in mind. > > In particular, I have found that dynamicsymbols do not work with dsolve, > solveset.nonlinsolve and series expansions. > > See this issue: > https://github.com/sympy/sympy/issues/12044 > > I will have to use these when I tackle the solvers after I am done with > parsing the basic physics entities. > It would be great if someone could look into this. dynamicsymbols are just SymPy Functions of t, so anything that doesn't work with them should be fixed. Aaron Meurer > > -- > 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 sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > 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/2862ac25-6b9d-47a2-aec9-eae6c48d3463%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 sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. 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/CAKgW%3D6Kixhrww-nebhf3UvD_Vmpx2bY1BMxkZj6J%2BH9xZS5r4A%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
