R help - Sep 2012 - Warning Message: In if (deparse(params[[nm]][[3]]) != "1")

I am using the gnls procedure in nlme package to fit a nonlinear model as:
nl.fit<-gnls(Y ~ b0*exp(b1/X),
                  data = data1,
                  params=list(
                 b0~p1+I(p1^2)+p2+I(p2^2)+p3+I(p3^2)+p5+p6
                 b1~p8+p2+I(p2^2)+p3+p9+p10+p11),
                 start = c(25,0,0,0,0,0,0,0,0,-8.6,0,0,0,0,0,0,0),
                 weights=varPower(form =~ X)
                 )

When I run this code, the model getts fitted but there are 2 warning
messages as
Warning messages:
1: In if (deparse(params[[nm]][[3]]) != "1") { :
  the condition has length > 1 and only the first element will be used
2: In if (deparse(params[[nm]][[3]]) != "1") { :
  the condition has length > 1 and only the first element will be used

I have no idea what there messages imply.
Any idea from somebody?

Charles




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Usually the source of such errors is the data you provide to the function. Since
you have not followed the posting guide and provided a reproducible example, we
are under a significant handicap in troubleshooting your problem.
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obuyacharles <csabatia at vt.edu> wrote:
>I am using the gnls procedure in nlme package to fit a nonlinear model
>as:
>nl.fit<-gnls(Y ~ b0*exp(b1/X),
>                  data = data1,
>                  params=list(
>                 b0~p1+I(p1^2)+p2+I(p2^2)+p3+I(p3^2)+p5+p6
>                 b1~p8+p2+I(p2^2)+p3+p9+p10+p11),
>                 start = c(25,0,0,0,0,0,0,0,0,-8.6,0,0,0,0,0,0,0),
>                 weights=varPower(form =~ X)
>                 )
>
>When I run this code, the model getts fitted but there are 2 warning
>messages as
>Warning messages:
>1: In if (deparse(params[[nm]][[3]]) != "1") { :
>  the condition has length > 1 and only the first element will be used
>2: In if (deparse(params[[nm]][[3]]) != "1") { :
>  the condition has length > 1 and only the first element will be used
>
>I have no idea what there messages imply.
>Any idea from somebody?
>
>Charles
>
>
>
>
>--
>View this message in context:
>http://r.789695.n4.nabble.com/Warning-Message-In-if-deparse-params-nm-3-1-tp4643638.html
>Sent from the R help mailing list archive at Nabble.com.
>
>______________________________________________
>R-help at r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

I am not sure if it is possible to provide a data set sufficient to fit this
model and reproduce the error.  However, I noticed that the warnings no
longer show up when the number of predictors for b0 and b1 in b0~ .... and
b1 ~.... is small (3 to 5). Could this be an effect too many
"subcoefficients" of b0 and b1?

charles



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