Re: how can I solve a function Erfc
- To: mathgroup at smc.vnet.net
- Subject: [mg48494] Re: how can I solve a function Erfc
- From: "Peter Pein" <petsie at arcor.de>
- Date: Wed, 2 Jun 2004 04:22:00 -0400 (EDT)
- References: <c99d7f$k3b$1@smc.vnet.net> <c9ccj1$5sn$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"David W. Cantrell" <DWCantrell at sigmaxi.org> schrieb im Newsbeitrag news:c9ccj1$5sn$1 at smc.vnet.net... > "Florian Jaccard" <florian.jaccard at eiaj.ch> wrote: > [snip] > > In[9]:= L/(4*(Dg*t)^(1/2)) == InverseErfc[0.9] > > > > In[10]:= Solve[{%, Dg == 5*10^5}, t] > > My question now is: Since [2] (using 0.9) works, > why does [1] (using 9/10 instead) fail? > > > In[1]:= Solve[L/(4*(Dg*t)^(1/2)) == InverseErfc[9/10], t] > > Out[1]= {} > > In[2]:= Solve[L/(4*(Dg*t)^(1/2)) == InverseErfc[0.9], t] > > Out[2]= {{t -> (7.916014709627096*L^2)/Dg}} > > > Surely [1] indicates a bug of some sort. > > David Cantrell In[1]:= Solve[L/(4*(Dg*t)^(1/2)) == InverseErfc[9/10], t] Out[1]= {{t -> L^2/(16*Dg*InverseErf[ Infinity, -(9/10)]^2)}} ?? -- Peter Pein, Berlin to write to me, start the subject with [