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Re: Rearrange equation II

  • To: mathgroup at smc.vnet.net
  • Subject: [mg111630] Re: Rearrange equation II
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Sun, 8 Aug 2010 07:20:56 -0400 (EDT)

On 8/7/10 at 1:29 AM, tonja.krueger at web.de (Tonja Krueger) wrote:

>I probably didn't explain properly: I've got a function G(x), which
>is:

>-(Sqrt[\[Pi]/2]*Erfc[x]*(-\[Mu]+Log[x]))/(2*Sqrt[\[Pi]]*\[Sigma])

>The parameters mu and sigma are unknown. I would like to convert the
>formula so it has the Form: x=..... (So I kind of want to inverse
>the function). Is there a way to do so, with mu, sigma and x[i] not
>known?

What you have described above simply isn't possible. You are
asking for a symbolic expression that is F(x) such that F(G(x))
gives x. No such F(x) exists for your G(x). The only possibility
to invert G(x) is to use numerical techniques which require mu
and sigma to be given specific numerical values.



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