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Re: What does +- mean?


Hi, This seems to be the bug. This is seen looking
at FullForm of your series

In[1]:=
FullForm[Series[
    Sqrt[-2^(-1) + x^2],
    {x, 0, 4}]]

Out[1]//FullForm=
FullForm[SeriesData[x, 0,
    {Complex[0, 1]*1/Sqrt[2],
     0,
     (Complex[0, -1])*1/Sqrt[2],
     0,
     (Complex[0, Rational[-1, 2]])*1/Sqrt[2]},
     0, 5, 1]]

This is what we should expect, and hence we have the display bug.
It seems to be only present is coefficient of expansion involve
radicals. The following modification of your example displays OK.

Series[ -1/4 + x^2, {x, 0, 4} ]

Regards,
Oleksandr Pavlyk

Lautaro Vergara wrote:

> Hi,
> 
> I have found (v. 5.0) an extrange thing: when one expands, e.g.,
> 
> Series[Sqrt[-1/2+x^2],{x,0,4}]
> 
> there appear a +- sign (which is correctly not present when one changes
> -1/2 by -1)
> 
> is this a bug or a feature?
> 
> Thanks
> 
> L. Vergara


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