On Feb 24, 2011, at 4:33 AM, Alexander Eberspächer wrote:

> Hello,
> 
> On Thu, 24 Feb 2011 09:58:59 +0300
> "Alexey U. Gudchenko" <[email protected]> wrote:
> 
>> And I have some little question about Laurent.
>> 
>> exp(1/x).series(x, oo) = 1 + 1/x + 1/(2*x**2) ...
>> 
>> Is it Laurent or power series?
> 
> In my use of maths language, this is a Laurent series as negative
> powers of x contribute. Power series (or, in this case, Taylor series)
> contain only exponents in [0; oo). So I would call this expansion a
> Laurent series about the point x=oo.
> 
> Quickly browsing through the Mathematica 8 documentation, it seems that
> Mathematica does not offer more much functionality than SymPy does (or
> will do with that Series branch). The documentation also is fuzzy about
> terminology. It describes that Series[] gives a series that may be a
> (truncated ) Taylor series or another, more general type of series with
> generalized powers (such as fractional powers). I haven't found a
> command to explicitly generate Laurent series.
> 
> Cheers
> 
> Alex

I think Mathematica can do more than SymPy, because for example, if you type 
"series of sin(x)" into Wolfram|Alpha 
(http://www.wolframalpha.com/input/?i=series%20of%20sin(x)), you get both 
x-x^3/6+x^5/120-x^7/5040+x^9/362880+O(x^10) and sin(x) = 
sum_(k=0)^infinity((-1)^k x^(1+2 k))/((1+2 k)!).

Aaron Meurer

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