#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:
> * #6344
> * #6480
> * #6756
> * #12796
> * #7401 (similar topic, not same issue)
>
> 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 - allow typesetting in "diff" format (possibly only as non-default
option)
* #6756 - add ''input'' to Sage in "diff" format for derivatives (the most
controversial)
* #6480 - clarify or fix substituting functions inside of symbolic
derivatives
* #7401 - bug in our interaction with Maxima with evaluating derivative at
a point (needs work due to multivariate derivatives not being there)
* #12796 - allow evaluation at points
and this discussion:
https://groups.google.com/forum/#!topic/sage-devel/_xD5lymnTuo
--
Comment (by kcrisman):
Okay, at least now I actually understand what the different tickets are
about. Phew.
--
Ticket URL: <http://trac.sagemath.org/ticket/17445#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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