On Thu, 3 Mar 2022 at 20:28, Aaron Meurer <[email protected]> wrote:
> On Thu, Mar 3, 2022 at 8:28 AM Chris Smith <[email protected]> wrote:
> >
> > Although the dict=True or set=True will give a standard output, can we at
> > least unify the case for when variables are given so we always get a list
> > of one or more dictionaries? So the above would be `[{x: -sqrt(y)}, {x:
> > sqrt(y)}]` and `[{x: y}]`, respectively. This would then make `solve`
> > always give a list of a) values for a univariate expression, b) a list of
> > one or more dictionaries for every other case. (Case (a) will give a list
> > of dictionaries if `dict=True`.)
>
> Changing the output type could break code that solves a specific
> equation. I am doubtful whether any users actually understand the
> output type behavior of solve without the dict=True flag. So
> personally I think we should clean it up. We already recommend using
> dict=True to get consistent output types, and this would only affect
> users who aren't doing that.
It would be much better if solve always worked like that but obviously
that's not a backwards compatible change and I'm not sure what would
break. I don't think that the type of the output should depend on the
number of solutions although it could depend on the type of the
arguments (e.g a single equation vs a list of equations). At the
moment the type of the output can depend on the equations themselves
which is wildly awkward:
In [3]: solve([x-1], [x])
Out[3]: {x: 1}
In [4]: solve([x**2-1], [x])
Out[4]: [(-1,), (1,)]
The ideal output for solve is absolutely a list of dicts though and it
would be good to make that the default at least when given a list of
equations. I guarantee that a lot of notebooks or other little bits of
code will depend on each of these random special cases though.
--
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/CAHVvXxROqs0CpGmSX2%3Dk8xJgTos9FPpP1x0GYP0aHCdiYErDnA%40mail.gmail.com.
