#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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Old description:
> Taking the derivative of a symbolic function returns the D-notation:
> sage: var('x y z')
> sage: f(x) = function('f',x,y,z);
> sage: f(x).diff(x,y)
> D[0, 1](f)(x, y, z)
>
> Unfortunately, the meaning of this notation is not documented anywhere,
> neither in diff(), nor in derivative() nor in function(). There is a ton
> of tickets about improving ambiguities and malfunctions related to this
> notation, but it would be very helpful to at least document how it is
> supposed to work and what it means if a user sees output as above.
>
> See here for related tickets:
> http://trac.sagemath.org/ticket/6344
> http://trac.sagemath.org/ticket/6480
> http://trac.sagemath.org/ticket/6756
> http://trac.sagemath.org/ticket/12796
>
> and this discussion:
> https://groups.google.com/forum/#!topic/sage-devel/_xD5lymnTuo
New description:
Taking the derivative of a symbolic function returns the D-notation:
sage: var('x y z')
sage: f(x) = function('f',x,y,z);
sage: f(x).diff(x,y)
D[0, 1](f)(x, y, z)
Unfortunately, the meaning of this notation is not documented anywhere,
neither in diff(), nor in derivative() nor in function(). There is a ton
of tickets about improving ambiguities and malfunctions related to this
notation, but it would be very helpful to at least document how it is
supposed to work and what it means if a user sees output as above.
See here for related tickets:
* #6344
* #6480
* #6756
* #12796
and this discussion:
https://groups.google.com/forum/#!topic/sage-devel/_xD5lymnTuo
--
Comment (by kcrisman):
Are there times where this notation is ambiguous, though? I seem to
recall that being the case.
Also, I think something about this should show up at the top of the
"sage/calculus/calculus.py" file as well. It's a constant source of
questions I don't really know the answer to.
--
Ticket URL: <http://trac.sagemath.org/ticket/17445#comment:2>
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