That's great. I suggest not trying to add everything at once. Probably some changes will need to be made and there are other steps like tests and so on that would need to be added if there aren't already tests in the right format.
Is your code publicly viewable already? For example if you put it in a github repo/gist then you can send a link here. Oscar On Thu, 17 Jun 2021 at 20:17, אוריאל מליחי <[email protected]> wrote: > Hello everyone! > > I finally completed implementing these functions. > > > *Quick reminder:* The main function is called *is_implied_by* and it gets > a set of linear inequalities and a target linear inequality and return > whether the target is implied by the set or not. > > Two other functions are *find_values_interval *and > *simplify_linear_inequalities.* > > * find_values_interval* gets a set of linear inequalities and a target > expression (expr) and returns an interval of [min possible value for expr, > max possible value for expr]. > > *simplify_linear_inequalities* gets a set of linear inequalities and > returns a simplified set (redundant inequalities are removed). > > Now I would like to know what are the next steps for me to do in order to > get my implementation into sympy. This is my first time contributing so > detailed explanation would be really helpful. > > > > On Thursday, 18 February 2021 at 18:28:38 UTC+2 [email protected] > wrote: > >> Den tors 18 feb. 2021 kl 14:36 skrev Oscar Benjamin < >> [email protected]>: >> >>> On Thu, 18 Feb 2021 at 11:32, Oscar Gustafsson >>> <[email protected]> wrote: >>> > >>> > After currently using Mathematica for similar things, I would just >>> like to encourage you to provide some nice method to simplify constraints >>> of piecewise functions using your simplifier, including additional >>> constraints on the range of variables (as SymPy doesn't have a way to put >>> ranges on variables). That doesn't really exist in Mathematica >>> (Assuming[..., Simplify[piecewise]) doesn't always seems to simplify as far >>> as possible). >>> > >>> > Something like >>> > simplify_piecewise_range(piecewisefunction, common_constraints) >>> > That adds the common_constraints to each region constraint and applies >>> your method. (Possibly, optionally, removing the common_constraints from >>> the final regions if feasible.) >>> >>> I imagined that this would be something that the new assumptions could >>> handle in refine. Something like: >>> >>> p = Piecewise((x, x < 1), (x**2, True)) >>> p = refine(p, abs(x) < 1) >>> >>> The idea would then be that e.g. when you have Integral(f, (x, a, b)) >>> then the integration routine can do >>> >>> f = refine(f, (a < x) & (x < b)) >>> >> Yes, a different assumption system will also do the trick. But until that >> is in place, this would be a useful short-cut for a specific use case. >> >> >> > There is an old PR which may be useful to revive in relation to this: >>> https://github.com/sympy/sympy/pull/17443 although sort of independent. >>> > >>> > It will also be useful to have a function that can replace Min/Max >>> expressions with linear inequalities (and possibly back again). Right now >>> there is some logic to convert from linear inequalites to Min/Max, but not >>> back. As far as I recall. (There may be a PR doing the Min/Max to linear as >>> well, but not really sure.) >>> >>> Is this what you mean? >>> >>> In [1]: Min(x, y).rewrite(Piecewise) >>> Out[1]: >>> ⎧x for x ≤ y >>> ⎨ >>> ⎩y otherwise >>> >>> Perhaps there could be a rewrite(Max) for Piecewise. >>> >>> I seem to recall that I did something that rewrote/simplified, probably >> as part of the pattern based logic simplification, >> And(x <= y, x <= z) >> to >> x <= Min(y, z) >> >> At some later stage I realized it was sometimes a bad idea (as the logic >> simplification sometimes worked better without the Min/Max, do not recall >> exactly) and I sort of regretted introducing that rewrite, but cannot >> recall if the reverse operation was ever introduced. Piecewise may work >> though, but I believe that for the linear inequality simplifier it may be >> better to rewrite x <= Min(y, z) back to And(x <= y, x <= z) . >> >> BR Oscar >> >> -- > 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 view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/07668755-217b-4487-805d-1faefd70191bn%40googlegroups.com > <https://groups.google.com/d/msgid/sympy/07668755-217b-4487-805d-1faefd70191bn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAHVvXxSRzs-68e4ENKrYH%2B%3DF5oeqbo0x92C1%2Bs161KcxUcLDhw%40mail.gmail.com.
