Opened 5 years ago
Last modified 4 years ago
#24861 needs_work defect
Option to hold for derivative
Reported by:  Vaibhav Karve  Owned by:  

Priority:  trivial  Milestone:  sage8.4 
Component:  calculus  Keywords:  hold 
Cc:  Merged in:  
Authors:  Ralf Stephan  Reviewers:  
Report Upstream:  N/A  Work issues:  
Branch:  u/rws/option_to_hold_for_derivative (Commits, GitHub, GitLab)  Commit:  453cf14cdc3615d781d0dcd57daa95b9e45d5b5a 
Dependencies:  Stopgaps: 
Description
It would be nice to have the output of
(x^3).diff(x, hold=True)
look like
$$ \frac{\partial}{\partial x}x^3 $$
Change History (5)
comment:1 Changed 5 years ago by
comment:2 Changed 5 years ago by
Branch:  → u/rws/option_to_hold_for_derivative 

comment:3 Changed 5 years ago by
Commit:  → 453cf14cdc3615d781d0dcd57daa95b9e45d5b5a 

Branch pushed to git repo; I updated commit sha1. New commits:
453cf14  24861: handle multi diffs

comment:4 Changed 5 years ago by
Authors:  → Ralf Stephan 

Milestone:  sagefeature → sage8.2 
Status:  new → needs_review 
Thanks for the report. This will be a useful addition to Sage.
comment:5 Changed 4 years ago by
Milestone:  sage8.2 → sage8.4 

Status:  needs_review → needs_work 
I agree this would be a nice addition; thanks for addressing this. Here are some comments.
In src/sage/functions/other.py
:
 Something like
(x).diff(x*x, hold=True)
returnsdiff(x, x^2)
instead of an error. Note also thatlatex((x).diff(x*x, hold=True))
causes a segfault.  The error message
wrong argument in diff
could be made more helpful; perhaps something likeall arguments to diff must be symbols or numerical values
. This should be tested as well.  The LaTeX output should include parentheses around the expression (probably with
\left
and\right
), otherwise something likelatex((x^3+y).diff(x,2,y,2, hold=True))
returns{\frac{\partial^{4}}{{\partial x^2}{\partial y^2}} x^{3} + y}
which is incorrect.
In src/sage/symbolic/expression.pyx
:
 the
hold
parameter should be added to the docstring ofderivative
. I also noticed a typo in the first line of the docstring as well:this expressions
>this expression
.
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Although we don't exactly have already a ticket for this, see the related #17445 and #15021.