[R] a symbolic derivative question, please

[Erin Hodgess]

Great!
thank you!
Sincerely,
Erin


On Fri, Jan 9, 2015 at 2:36 PM, Duncan Murdoch <murdoch.duncan at gmail.com>
wrote:

> On 09/01/2015 2:04 PM, Erin Hodgess wrote:
> > One more thing, please:  (just like Columbo)
> >
> > Is there a work-around for this, please?
>
> I did some work with John Nash a few months ago that gave symbolic
> derivative code that was a bit more flexible than the built-in code.
> It's on R-forge in the nls14 package.
>
> With that package, you get the same error as in base, but you can do
>
> newDeriv(`[`(x,y), stop("no derivative when indexing"))
>
> and then fnDeriv() (the nls14 replacement for deriv()) works on your
> example.
>
> Duncan Murdoch
>
> >
> > Thanks again,
> > Erin
> >
> >
> > On Fri, Jan 9, 2015 at 1:09 PM, Richard M. Heiberger <rmh at temple.edu>
> wrote:
> >
> >> `[` is a function.  So the deriv program is seeing
> >>
> >> `[`(y,3)*r1 + r2
> >>
> >>> letters[5]
> >> [1] "e"
> >>> `[`(letters, 5)
> >> [1] "e"
> >>
> >> On Fri, Jan 9, 2015 at 12:31 PM, Erin Hodgess <erinm.hodgess at gmail.com>
> >> wrote:
> >>> Hello!
> >>>
> >>> I have the following:
> >>>
> >>> zzz <- expression(y[3]*r1 + r2)
> >>> deriv(zzz,c("r1","r2"))
> >>> Error in deriv.default(zzz,c("r1","r2")) :
> >>>    Function '`[`' is not in the derivatives table
> >>>
> >>> What am I missing, please?  Since y is not one of the variables that is
> >>> being "acted upon", why is the [] an issue, please?
> >>>
> >>> Thank you for any help!
> >>>
> >>> Sincerely,
> >>> Erin
> >>>
> >>>
> >>> --
> >>> Erin Hodgess
> >>> Associate Professor
> >>> Department of Mathematical and Statistics
> >>> University of Houston - Downtown
> >>> mailto: erinm.hodgess at gmail.com
> >>>
> >>>         [[alternative HTML version deleted]]
> >>>
> >>> ______________________________________________
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> >>> 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.
> >>
> >
> >
> >
>
>


-- 
Erin Hodgess
Associate Professor
Department of Mathematical and Statistics
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com

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