Thanks to everybody! On Monday, September 13, 2021 at 3:56:47 PM UTC+3 Oscar wrote:
> Think about things that are literally not numbers: > > In [9]: Interval(1, 2).is_number > Out[9]: False > > In [10]: ImmutableMatrix([[1, 2], [3, 4]]).is_number > Out[10]: False > > > On Mon, 13 Sept 2021 at 13:00, Chris Smith <[email protected]> wrote: > >> To confirm, if you mean that it is free from any Symbol (free or bound) >> then `not expr.has(Symbol)` will be best. But if you consider `Integral(x, >> (x, 1, 2))` as a number then you should use `is_number` or `free_symbols`, >> with `expr.is_number` failing sooner than `not expr.free_symbols` if the >> expression has a free symbol. (So if you suspect the expression has free >> symbols then use `is_number`, else `free_symbols`). >> >> `f.is_number != (not bool(f.free_symbols))` should be an invariant for >> Expr, but SymPy also deals with Booleans, so `S.true.is_number` is False >> and `S.true.free_symbols` is empty. >> >> /c >> >> On Sunday, September 12, 2021 at 11:56:23 PM UTC-5 [email protected] >> wrote: >> >>> Are there any cases when f.is_number != (not bool(f.free_symbols))? >>> >>> If I have an arbitrary expression, what is the correct way to check >>> whether it has variables? >>> >>> Thank you. >>> >> -- >> 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/9af46205-ce22-494c-a604-c27b6682fa96n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/sympy/9af46205-ce22-494c-a604-c27b6682fa96n%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/8717be3c-0286-4741-900c-94e21573f3c5n%40googlegroups.com.
