
Hi

While trying to simplify the model to create a small reproducible example I have found my error.

Previously in order to try and solve another problem, I had changed my Model function. However I had made a mistake in doing this and caused the function to always output 0. Fixing this error has now fixed the error and brought me back to the original problem.

I now get:
singular gradient matrix at initial parameter estimates

It is a very complex model so I am unsure how to fix this yet, but I am going to try and use the brute-force algorithm from nls2.

Thanks for the help.

Matthew

Date: Wed, 1 Aug 2012 16:18:07 -0700
From: ml-node+s789695n4638799h88@n4.nabble.com
To: matthew_bk8@hotmail.com
Subject: Re: R_nls_iter error: REAL() can only be applied to a 'numeric', not a 'logical'



	On Wed, Aug 1, 2012 at 11:40 AM, matthewbk <[hidden email]> wrote:

> Hi

>

> I am using the nls function in R however it is causing the following error:

> REAL() can only be applied to a 'numeric', not a 'logical'

>

> Using traceback shows this occurs after the .Call(R_nls_iter, m, ctrl,

> trace) call. However I do not know how to debug this further to find out

> what is causing the error.

>

> The data I give the nls call definitely starts as numeric. The data.frame is

> generated by using the following:

>

> d = data.read('data.csv', header=FALSE)

> x = as.numberic(d[,1])

> y = as.numberic(d[,2])

> z = as.numberic(d[,3])

> ...

Certainly no "b" ?


>

> dat = data.frame(x,y,z...)

>

> nls is started by calling:

> mdl = nls(y ~ Model(x,y,z....,b1,b2,b3), data = dat)

>

> Thanks in advance for any help.

>

> Matthew

>

>

This one's actually tricky since that's an error arising from the C

code. I don't think there's an error in the C code, but let's do some

work on debugging. To start with, can you make a small reproducible

example following the advice given here:


http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example

To wit, we don't have your "dat" data (use dput! but please, only a

small-ish subset)  nor the function "Model" and the lines of code

replaced by "..." worry me as well.


Best,

Michael


>

>

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