Re: [R] Solving Systems of Non-linear equations

From: Martin Maechler <>
Date: Fri 02 Dec 2005 - 00:55:45 EST

>>>>> "YNoel" == NOEL Yvonnick <> >>>>> on Thu, 01 Dec 2005 14:42:44 +0100 writes:

    YNoel> On 11/30/05, Scott Story <> wrote:
>>> I am trying to write a function that will solve a simple system of
>>> nonlinear equations for the parameters that describe the beta
>>> distribution (a,b) given the mean and variance.
>>> mean = a/(a+b)
>>> variance = (a*b)/(((a+b)2) * (a+b+1))
>>> Any help as to where to start would be welcome.
    YNoel> The simplest way to go is probably to use the fitdistr function in MASS     YNoel> package.

yes, definitely for estimating the beta parameters - namely do something smarter than the above moment estimates.

However, I (and probably most respondents to this thread) believe that the question was more general (as the subject indicates) about solving non-lin eq systems, rather than about estimating the beta parameters (by a sub-optimal method).

Martin Maechler, ETH Zurich mailing list PLEASE do read the posting guide! Received on Fri Dec 02 01:00:38 2005

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