Comment #2 on issue 3965 by [email protected]: sum of chebyshev polys
fails to evaluate
http://code.google.com/p/sympy/issues/detail?id=3965
The issue boils down to
In [6]: chebyshevt(i, 2).diff(i)
Out[6]:
d
──(chebyshevt(i, 2))
di
So it remains unevaluated. In particular,
In [4]: (2 + chebyshevt(i, 2).diff(i).subs(i, 2)).evalf()
Out[4]:
⎛d ⎞│
⎜──(chebyshevt(i, 2))⎟│ + 2.0
⎝di ⎠│i=2
doesn't lead to a number, hence the symbolic relational.
Unrelated, but just
In [4]: (chebyshevt(i, 2).diff(i).subs(i, 2)).evalf()
leads to a recursion error.
So there are a few things that need to be fixed here:
- The Sum evalf routine needs to be more careful against symbolic
relationals:
- Subs(Derivative).evalf() should work
- (chebyshevt(i, 2).diff(i).subs(i, 2)).evalf() shouldn't lead to a
recursion error.
--
You received this message because this project is configured to send all
issue notifications to this address.
You may adjust your notification preferences at:
https://code.google.com/hosting/settings
--
You received this message because you are subscribed to the Google Groups
"sympy-issues" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sympy-issues.
For more options, visit https://groups.google.com/groups/opt_out.
