Note also that function('f')(y, x) does not actually create a function with
named arguments.
It is an ordinary symbolic expression that evaluates the undefined function
f of unspecified arity.
Unbound variables in ordinary symbolic expression use alphabetical order.
https://trac.sagemath.org/ticket/32227 attempts to deprecate calling
"arguments" on such expressions.
To create a function with named arguments, you would have to use callable
symbolic expressions:
sage: x, y = var('x y')
sage: function('f')(y, x).function(y, x)
(y, x) |--> f(y, x)
sage: _.arguments()
On Tuesday, March 8, 2022 at 9:06:20 AM UTC-8 Matthias Koeppe wrote:
> Yes, callable symbolic expressions need a lot of fixes. See meta-ticket
> https://trac.sagemath.org/ticket/28434
>
> On Tuesday, March 8, 2022 at 7:23:15 AM UTC-8 Eric Gourgoulhon wrote:
>
>> Hi,
>>
>> We have currently
>>
>> sage: x, y = var('x y')
>> sage: fyx = function('f')(y, x)
>> sage: fyx.arguments()
>> (x, y)
>>
>> which is just the reverse of the expected output.
>>
>> Similarly, we have
>>
>> sage: atan2(y,x).arguments()
>> (x, y)
>>
>> Taking a look at the code, one sees that fyx.arguments() calls
>> fyx.variables(), which returns a "sorted tuple of variables that occur in
>> this expression" (according to the documentation). The "sorted" action
>> explains the result. But the latter remains plain false.
>>
>> Note that SymPy provides the correct result:
>>
>> sage: fyx._sympy_().args
>> (y, x)
>> sage: atan2(y,x)._sympy_().args
>> (y, x)
>>
>> Eric.
>>
>
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sage-devel/0def2d95-132b-492c-9006-df09383ea63en%40googlegroups.com.
