: 21
Date: Wed, 14 Nov 2012 03:04:56 -0800 (PST)
From: muzammil786
To: r-help@r-project.org
Subject: Re: [R] problem in fitting model in NLS function
Message-ID: <1352891096449-4649473.p...@n4.nabble.com>
Content-Type: text/plain; charset=us-ascii
Dear David,
I am having a similar proble
Dear David,
I am having a similar problem on this data (given below). I have tried
several starting values for a and b, but it is consistently giving me:
*fm <- nls(y~f(x,a,b), data.frame(x,y), start=c(a=1,b=1))
Error in numericDeriv(form[[3L]], names(ind), env) :
Missing value or an infinity
I am no expert on nls() but since I haven't seen any replies to your
post, I'll chip in:
(1) I am mystified as to why nls() is giving that error about a
"singular" (???)
gradient.
(2) That being said, I think your parameterisation of the objective function
is a bit flaky. I would use
Ram
These errors often show up with starting values that are poor and wander
into 'illegal' territory (divide by zero, exp(large number),
log(negative or zero), etc. Consider putting constraints on the
parameters (?nls will guide you) and working harder to get starting
values by plotting the d
Dear R users,
I am struggling to fit expo-linear equation to my data using "nls"
function. I am always getting error message as i highlighted below in yellow
color:
Theexpo-linear equation which i am interested to fit my data:
response_variable = (c/r)*log(1+exp(r*(Day-tt))), where "
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