[Maxima-bugs] [ maxima-Bugs-1692082 ] tlimit(s/(1+s^2)/sinh(x*T), s, inf)

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Bugs item #1692082, was opened at 2007-03-31 14:21
Message generated for change (Comment added) made by dgildea
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Category: Lisp Core - Limit
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: tlimit(s/(1+s^2)/sinh(x*T), s, inf)

Initial Comment:
In Maxima 5.11.0:

  tlimit(s/(1+s^2)/sinh(x*T), s, inf);
  Is T positive, negative, or zero?
  p
  Invalid call to var-expand.

(Cf. Maxima list: March 31, 2007, "bug in tlimit?").

Stavros mentioned on the list that
taylor(exp(x)-exp(-x), x, inf, 2) returns a sensible result whereas taylor((exp(x)-exp(-x))/2, x, inf, 2)
triggers an internal error.


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>Comment By: Dan Gildea (dgildea)
Date: 2007-09-08 15:12

Message:
Logged In: YES 
user_id=1797506
Originator: NO

fixed in hayat.lisp rev 1.27

(%i21) tlimit(s/(1+s^2)/sinh(x*T), s, inf);
Is  x*T  positive or negative?
pos;
(%o21) 0

(%i22) taylor((exp(x)-exp(-x))/2, x, inf, 2);
(%o22) 1/(2*%e^-x)-%e^-x/2


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