Re: ProductLog[-Pi/2]

*To*: mathgroup at smc.vnet.net*Subject*: [mg44176] Re: [mg44160] ProductLog[-Pi/2]*From*: "Peter Pein" <nospam at spam.no>*Date*: Sat, 25 Oct 2003 06:26:26 -0400 (EDT)*References*: <200310240824.EAA04419@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

onlinehelp: ProductLog[z] has a branch cut discontinuity in the complex z plane running from -infinity to -1/e. ProductLog[k, z] for integer k>0 has a branch cut discontinuity from -infinity to 0. Peter Pein, Berlin petsie at arcAND.de replace && by || to write to me ----- Original Message ----- From: "Jean-Claude Poujade" <poujadej at yahoo.fr> To: mathgroup at smc.vnet.net Subject: [mg44176] [mg44160] ProductLog[-Pi/2] > ProductLog[-Pi/2] should return I Pi/2 but doesn't... > > In[1] := w E^w /. w -> I Pi/2 > Out[1] = -Pi/2 > > In[2] := ProductLog[-Pi/2] // FullSimplify > Out[2] = ProductLog[-Pi/2] > > In[3] := ProductLog[-Pi/2] // N // Chop > Out[3] = 1.5708 I > > Could someone explain ? (I use Mathematica 4.1) > > --- > jcp >

**References**:**ProductLog[-Pi/2]***From:*poujadej@yahoo.fr (Jean-Claude Poujade)