Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2005

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Bug with Limit, Series and ProductLog ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg61465] Re: Bug with Limit, Series and ProductLog ?
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 19 Oct 2005 02:17:31 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <dj26kc$bc7$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

and the essential singularity at x==0
of

ProductLog[Exp[a/x]/x]-a/x

does not matter ?

Regards
  Jens
"did" <didier.oslo at hotmail.com> schrieb im 
Newsbeitrag news:dj26kc$bc7$1 at smc.vnet.net...
| With Mathematica 5.2 Windows I obtain
|
| In[1]:=Limit[ ProductLog[Exp[a/x]/x]-a/x,x->0]
| Out[1]= -Log[a]
|
| which seems correct. But, setting a=1, I get
|
| In[2]:=Limit[ ProductLog[Exp[1/x]/x]-1/x,x->0]
| Out[2]=-8
|
| which is inconsistent with the previous result
| (except if Log[1] is Infinity !).
|
| Worse, with Series I get
|
| In[3]:=Series[ 
ProductLog[Exp[a/x]/x]-a/x,{x,0,5}]
|
| Out[3]=\!\(\*
|  InterpretationBox[
|    RowBox[{\(-\(a\/x\)\), "+", "Indeterminate", 
"+",
|      InterpretationBox[\(O[x]\^6\),
|        SeriesData[ x, 0, {}, -1, 6, 1],
|        Editable->False]}],
|    SeriesData[ x, 0, {
|      Times[ -1, a], Indeterminate}, -1, 6, 1],
|    Editable->False]\)
|
| Setting a=1 in the Series gives a complex 
answer.
|
| How can I workaround the problem and get the 
correct
| expansion for In[3]?
| Thanks,
| D.
| 



  • Prev by Date: Re: Help with a function to return the 'age' of itself
  • Next by Date: Can the user create CellGroupingRules?
  • Previous by thread: Re: Bug with Limit, Series and ProductLog ?
  • Next by thread: Re: Bug with Limit, Series and ProductLog ?