[18725] in s-news-athena
Re: [S] nls( ) singular gradient matrix
daemon@ATHENA.MIT.EDU (Bruce McCullough)
Fri Jul 23 11:10:37 1999
Message-Id: <s7984b08.098@fcc.gov>
Date: Fri, 23 Jul 1999 10:58:28 -0400
From: "Bruce McCullough" <BMCCULLO@fcc.gov>
To: internet:internet:s-news@wubios.wustl.edu
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> While trying to fit a nonlinear model using nls( ), I get an error message
> that says I have a singular gradient matrix. I am not sure what causes
> this problem. Should I try different initial values of the parameters, or
> is the problem something else?
I have found that supplying analytic first derivatives
using deriv() can eliminate this problem (not always,
but sometimes). Supplying analytic derivatives
is well-described in V&R.
Bruce
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