Re: Bug in Mathematica 8 vs Mathematica 7: SeriesData

• To: mathgroup at smc.vnet.net
• Subject: [mg116867] Re: Bug in Mathematica 8 vs Mathematica 7: SeriesData
• From: DrMajorBob <btreat1 at austin.rr.com>
• Date: Thu, 3 Mar 2011 05:55:36 -0500 (EST)

```An infinite number of functions could have spawned that SeriesData object.

But that's one.

Bobby

On Wed, 02 Mar 2011 03:32:19 -0600, Daniel Lichtblau <danl at wolfram.com>
wrote:

> GidiL wrote:
>> Dear All!
>>
>> A long time ago I asked about the right way of using SeriesData for
>> multiple expansions.
>>
>> For example, if you want a multiple expansion of a metric in general
>> relativity, it is quite simple to input:
>> SeriesData[r, Infinity, {-1, -2, -3}, 0, 3, 1]
>> In Mathematica 7 this line is accepted as is, without any error
>> messages or problems.
>>
>> Yet, try this in Mathematica 8. You will get the following error
>> message:
>> SeriesData::sdatv: "First argument 1/r is not a valid variable."
>>
>> Does anyone know what has changed in version 8? Why should such a
>> simple expression be invalid in version 8 but be OK in version 7? I
>> find it quite strange.
>>
>> Would appreciate any help!
>>
>> Cheerio,
>>
>> Gideon
>>
>
> It works fine for me.
>
> In[411]:= SeriesData[r, Infinity, {-1, -2, -3}, 0, 3, 1]
>
> Out[411]= SeriesData[r,
> DirectedInfinity[1], {-1, -2, -3}, 0, 3, 1]
>
> But direct input of a XXXData object is generally a bad idea. Especially
> as these can change form over releases. Why not just use the Series that
> spawns it?
>
> In[420]:= Series[-1/(1 - 1/r)^2, {r, Infinity, 2}]
>
> Out[420]= SeriesData[r,
> DirectedInfinity[1], {-1, -2, -3}, 0, 3, 1]
>
> Daniel Lichtblau
> Wolfram Research
>

--
DrMajorBob at yahoo.com

```

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