[R] nls: formula error?
Gabor Grothendieck
ggrothendieck at gmail.com
Tue May 23 05:34:29 CEST 2006
The data= argument cannot be a matrix. See ?nls
On 5/22/06, H. Paul Benton <hpbenton at scripps.edu> wrote:
> So thanks for the help,
>
> I have a matrix (AB) which in the first column has my bin numbers so -4 - +4
> in 0.1 bin units. Then I have in the second column the frequency from some
> data. I have plotted them and they look roughly Gaussian. So I want to fit
> them/ find/optimize "mu", "sigma", and "A".
>
> So I call the nls function :
>
> nls_AB <- nls(x ~ (A/sig*sqrt(2*pi))* exp(-1*((x-mu)^2/(2*
> sig^2))),data=temp, start= list(A=0.1, mu=0.01, sig=0.5), trace=TRUE)
> Error in eval(expr, envir, enclos) : numeric 'envir' arg not of length one
>
> Temp looks like this:
> bin x
> [1,] -4.0 0
> [2,] -3.9 0
> [3,] -3.8 0
> .........etc
> [41,] 0.0 241
> [42,] 0.1 229
> [43,] 0.2 258
> [44,] 0.3 305
> [45,] 0.4 370
> [46,] 0.5 388
>
> So I don't get my error message. I looked at doing
> class(fo <- (x ~ (A/sig*sqrt(2*pi))* exp(-1*((x-mu)^2/(2* sig^2)))))
> terms(fo)
>
> and that seems to work. So if anyone has any ideas I would welcome them.
>
> Cheers,
>
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