Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2004
*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 2004

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

Search the Archive

Re: how can I solve a function Erfc

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48445] Re: how can I solve a function Erfc
  • From: "David W. Cantrell" <DWCantrell at sigmaxi.org>
  • Date: Sun, 30 May 2004 06:12:06 -0400 (EDT)
  • References: <c99d7f$k3b$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"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


> -----Message d'origine-----
> De : aude [mailto:montgermont.aude at ec-lille.fr]
> Envoyé : vendredi, 28. mai 2004 06:50
> À : mathgroup at smc.vnet.net
> Objet :  how can I solve a function Erfc
>
> Hi,
>
> I have to solve this function:
>
> Erfc[L/(4*(Dg*t)^(1/2))]= 0.9
>
> Dg is constant.
>
> Dg=5*10^5
>
> I want to plot t as a function of L.


  • Prev by Date: Plot Feature Concerning Number of Points Generated With Zero Function
  • Next by Date: Re: Removing non-numeric characters from a list
  • Previous by thread: Re: how can I solve a function Erfc
  • Next by thread: Re: how can I solve a function Erfc