Le 11/02/2011 00:09, Dan a ?crit :
> On Thu, 10 Feb 2011, Barton Willis wrote:
>
>> Apparently, Maxima sometimes tries a z =tan(x/2) substitution (expunged
>> from calculus books in the 1980s?)
>
> I don't know if you count
> <http://www.phy.cam.ac.uk/teaching/teachingfiles/formulae.pdf>; as a
> "calculus book", but it's right there on page 14 of the 2005 edition.
This reference seems to restrict the use of tan(x/2) substitution to the
case of rational functions of sin(x) and cos(x), which is not the case
of exp(sin(x)) and abs(sin(x)). I am not sure, but the ghost poles
introduced via the substitution may be much more difficult to treat
correctly in the case of non rational trig expressions.
Eric
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