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 [

```

• Prev by Date: Re: Number of roots from Solve?
• Next by Date: Re: 3D fitting of data points
• Previous by thread: Re: Help Browser
• Next by thread: Re: 3D fitting of data points