Your issue is that nls returns "singular gradient", but I believe the real
trouble is that
if or ifelse are not in the derivatives table. My own (experimental, but in
R-forge)
package nlmrt has nlxb to mirror nls but be much more aggressive in finding a
solution,
and it gives an error msg that i
Peter Ehlers wrote
>
>
>>
>
> If the above data is all you have, I wouldn't chugg too long.
> Looking at plots of Cfl~Pw and Cfl~Tsoil says to me that you
> have far too much variability to fit your model.
>
> You might find this plot instructive:
>
>library(rgl)
>plot3d(Pw, Tsoil, Cf
On 2012-05-17 08:40, DWatts wrote:
David Winsemius wrote
and provide commented, minimal, self-contained, reproducible code.
Still untested in absence of data.
Thank you, and my apologies for not giving some sample numbers. Below is a
short subset of the data set I'm working with.
Cfl=c
Hello,
I don't know if this is what you want, but your formula is equivalent to
nlstest=nls(Cfl~K*ifelse(Pw > z, 1, exp(-a*Tsoil))*exp(-b*Pw)+c
,start=c(K=5.5, a=0.1, b=0.1, c=2, z=5))
Hope this helps,
Rui Barradas
--
View this message in context:
http://r.789695.n4.nabble.com/nls-a
David Winsemius wrote
>
>>> and provide commented, minimal, self-contained, reproducible code.
>>
> Still untested in absence of data.
>
Thank you, and my apologies for not giving some sample numbers. Below is a
short subset of the data set I'm working with.
Cfl=c(2.61,4.21,2,2.75,7.47,1.2,3.2
On May 17, 2012, at 11:08 AM, David Winsemius wrote:
On May 17, 2012, at 10:06 AM, DWatts wrote:
Hi All,
I have a situation where I want an 'if' variable to be
parameterized. It's
entirely possible that the way I'm trying to do this is wrong,
especially
given the error message I get tha
On May 17, 2012, at 10:06 AM, DWatts wrote:
Hi All,
I have a situation where I want an 'if' variable to be
parameterized. It's
entirely possible that the way I'm trying to do this is wrong,
especially
given the error message I get that indicates I can't do this using
an 'if'
statement.
Hi All,
I have a situation where I want an 'if' variable to be parameterized. It's
entirely possible that the way I'm trying to do this is wrong, especially
given the error message I get that indicates I can't do this using an 'if'
statement.
Essentially, I have data where I think a relationship
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