[R] Unable to retrieve residual sum of squares from nls output

[Dennis Fisher]

Colleagues,

I am using "nls" successfully (2.11.1, OS X) but I am having difficulties retrieving part of the output - residual sum of squares.  I have assigned the output to FIT:
> > FIT
> Nonlinear regression model
>   model:  NEWY ~ PMESOR + PAMPLITUDE * cos(2 * pi * (NEWX - POFFSET)/PERIOD) 
>    data:  parent.frame() 
>     PMESOR PAMPLITUDE    POFFSET 
>    1153.02   -1183.09      24.58 
>  residual sum-of-squares: 1815056
> 
> Number of iterations to convergence: 8 
> Achieved convergence tolerance: 1.643e-08 

As you can see, the object contains "residual sum-of-squares: 1815056".  However, I can't figure out how to grab that value.   The tried using "str":
> > str(FIT)
> List of 6
>  $ m          :List of 16
>   ..$ resid     :function ()  
>   ..$ fitted    :function ()  
>   ..$ formula   :function ()  
>   ..$ deviance  :function ()  
>   ..$ lhs       :function ()  
>   ..$ gradient  :function ()  
>   ..$ conv      :function ()  
>   ..$ incr      :function ()  
>   ..$ setVarying:function (vary = rep(TRUE, length(useParams)))  
>   ..$ setPars   :function (newPars)  
>   ..$ getPars   :function ()  
>   ..$ getAllPars:function ()  
>   ..$ getEnv    :function ()  
>   ..$ trace     :function ()  
>   ..$ Rmat      :function ()  
>   ..$ predict   :function (newdata = list(), qr = FALSE)  
>   ..- attr(*, "class")= chr "nlsModel"
>  $ convInfo   :List of 5
>   ..$ isConv     : logi TRUE
>   ..$ finIter    : int 8
>   ..$ finTol     : num 1.64e-08
>   ..$ stopCode   : int 0
>   ..$ stopMessage: chr "converged"
>  $ data       : language parent.frame()
>  $ call       : language nls(formula = NEWY ~ PMESOR + PAMPLITUDE * cos(2 * pi * (NEWX -      POFFSET)/PERIOD), start = list(PMESOR = MESOR, PAMPLITUDE = AMPLITUDE,  ...
>  $ dataClasses: Named chr "numeric"
>   ..- attr(*, "names")= chr "NEWX"
>  $ control    :List of 2
>   ..$ maxiter : num 1000
>   ..$ warnOnly: logi TRUE
>  - attr(*, "class")= chr "nls"

However, none of these elements appears to contain the residual sum of squares.  
Help!  Thanks.

Dennis





Dennis Fisher MD
P < (The "P Less Than" Company)
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