#6956: [with patch, needs work] cannot differentiate cotangent
---------------------------+------------------------------------------------
Reporter: burcin | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-4.1.2
Component: symbolics | Keywords:
Reviewer: Burcin Erocal | Author: Tim Joseph Dumol
Merged: |
---------------------------+------------------------------------------------
Changes (by burcin):
* cc: jason, kcrisman (added)
* reviewer: => Burcin Erocal
Comment:
Thanks for the quick patch.
Here is my review:
* the keyword argument `diff_param` is only useful for multivariate
functions. In this case since all these functions are univariate, so we
know the argument is `args[0]`. You can safely drop the first two lines of
the `_derivative_()` methods and replace the third with `x = args[0]`.
* continuing the previous item, we should tell these functions they are
univariate. ATM, they silently drop the second argument:
{{{
sage: arccsc(a,b)
arccsc(a)
}}}
You can do this by giving `nargs=1` as a parameter to the base class
constructor.
* It is better to give the variable as an argument to `diff` in the
doctests, for example `diff(asech(x), x)`. I actually prefer
`asech(x).derivative(x)`, but this is your patch. :)
* The formula for the derivative of `asech(x)` you use is only true for x
real. You need `-1/(x * (x+1) * sqrt( (1-x)/(1+x) ))`.
* Similarly, the derivative of `acsch(x)` is `-1/(x^2 * sqrt(1 + 1/x^2)
)`
Can someone else check the derivatives to make sure there is no mistake?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6956#comment:2>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en
-~----------~----~----~----~------~----~------~--~---
