Status: New
Owner: ----
Labels: Type-Defect Priority-Medium Series WrongResult
New issue 4104 by [email protected]: Series expansion of trig functions
incorrect, except around 0
http://code.google.com/p/sympy/issues/detail?id=4104
Yesterday, I did this:
series(cos(x), x, pi, 3)
-1 + x^2/2 - x^4/24 + O(x^5)
This is incorrect according to Wolfram Alpha [1].
It should be:
-1 + (x - pi)^2/2 - (x - pi)^4/24 + O((x - pi)^5)
Basically, wherever there is an x in the sympy output, there should be an
(x - x0) in the correct answer. The sympy output is the right answer,
shifted over back to the origin on the x-axis.
[1] http://www.wolframalpha.com/input/?i=series+cos+around+pi+up+to+x%5E5
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