#17445: Missing documentation of derivative operator/notation
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Reporter: schymans | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-6.5
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: schymans | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by schymans):
Replying to [comment:21 nbruin]:
> Replying to [comment:20 schymans]:
> Or as `function('V')` for that matter. It seems misguided to me that
`function` admits an argument list. It has no meaning other than that
`function('V',x) == function('V')(x)`. I think the RHS syntax is much
clearer.
>
> > What would be the correct way to do the above consistently?
>
> A "symbolic function" in sage is simply something that can occur in the
"operator" slot of a symbolic expression. I don't think there is much
support for algebra on such objects. Hence the need to talk about `V(t)`
and `V(x)` (but better not in the same expression! Then you should use
`V(x,t)` and be consistent about the order in which `x,t` occur). Indeed,
going back to the topic of the ticket, I recommend that the whole
`function('f',x)` syntax gets deprecated or at least gets advised against
in the documentation. It pretends that sage can do something with it that
it can't.
Thanks, this clarifies a lot for me! I didn't realise I have to think of
'function' as of an operator. I have been thinking about using vars for
independent variables and functions for dependent variables, but as you
clarified, this was misguided. My thumbs up to deprecate the
`function('f',x)` syntax, then.
Is there another way to write an expression with dependent and independent
variables and then transparently differentiate it according to assumptions
which of the dependent variables are kept constant?
--
Ticket URL: <http://trac.sagemath.org/ticket/17445#comment:22>
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