On Fri, 14 Nov 2003, Liaw, Andy wrote:
> You should be able to use deriv(..., func=TRUE) to get a function returned,
> instead of an expression.
>
> If you need to use D, here's a rather clumsy way that seems to work:
>
> > dx2x <- D(expression(x^2), name="x"); dx2x
> 2 * x
> > eval(parse(text=paste("f <- function(x){",
> paste(deparse(dx2x), collapse=";"), "}")))
> > f
> function(x){ 2 * x }
I would have used
f <- function(x) {}
body(f) <- D(expression(x^2), name="x")
>
> HTH,
> Andy
>
> > From: Erin Hodgess [mailto:[EMAIL PROTECTED]
> >
> > Dear R People:
> >
> > When the D function is used for a symbolic derivative,
> > an expression is returned, which is fine.
> >
> > How do you change that expression to a function, please?
> >
> > I've been experimenting with substitute and deparse, but no
> > success yet.
> >
> > This is R 1.8.0 for Windows.
> >
> > thanks in advance for the help!
> >
> > Sincerely,
> > Erin Hodgess
> > mailto: [EMAIL PROTECTED]
>
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>
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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