Re: Bug? in PolyLog
- To: mathgroup at smc.vnet.net
- Subject: [mg21107] Re: Bug? in PolyLog
- From: Harald Giese <giese at dkrz.de>
- Date: Fri, 17 Dec 1999 01:21:07 -0500 (EST)
- Organization: Institut fuer Meereskunde, Universitaet Hamburg
- References: <831fc6$d9b@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Francois Grieu wrote: > > While trying to fix my Dickman function, I uncovered what appears > to be a bug with the numerical implementation of PolyLog. > It gives an imaginary part for PolyLog[2,x] for x>1 > when PolyLog[2,x] is purely real in this domain. > > Here is a session: > > Mathematica 4.0 Kernel for Power Macintosh > Copyright 1988-1999 Wolfram Research, Inc. > -- Terminal graphics initialized -- > > In[1]:= PolyLog[2, 2.0] > > Out[1]= 2.4674 - 2.17759 I > > In[2]:= Simplify[Im[PolyLog[2, 2]]] > > Out[2]= 0 > > Any clues ? I am interested by what happens for other releases > of Mathematica. > Francois, In[2]:= PolyLog[2, 2] Out[2]= PolyLog[2, 2] therefore Mathematica has nothing to simplify. Regards, Harald -- --- This message was entirely written using recycled electrons --- Harald Giese Email: giese at dkrz.de Phone: +49 (0)40 42838 5796; Fax: +49 (0)40 5605724 Institut fuer Meereskunde der Universitaet Hamburg (Institute of Oceanography of the University of Hamburg) Troplowitzstrasse 7, D-22529 Hamburg