[R] Derivative of a Function Expression

[Gabor Grothendieck]

And if f has brace brackets surrounding the body then do this:

f <- function(x) { x*x }
deriv(body(f)[[2]], "x", func = TRUE)

If you are writing a general function you can do this:

e <- if (identical(body(f)[[1]], as.name("{"))) body(f)[[2]] else body(f)
deriv(e, "x", func = TRUE)


On 9/3/07, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> One improvement.  This returns a function directly without having
> to create a template and filling in its body:
>
> deriv(body(f), "x", func = TRUE)
>
> On 9/3/07, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > The problem is that brace brackets are not in the derivatives table.
> > Make sure you don't have any.
> >
> > On 9/3/07, Alberto Vieira Ferreira Monteiro <albmont at centroin.com.br> wrote:
> > > Gabor Grothendieck wrote:
> > > >
> > > > Actually in thinking about this its pretty easy to do it without Ryacas
> > > > too:
> > > >
> > > > Df <- f
> > > > body(Df) <- deriv(body(f), "x")
> > > > Df
> > > >
> > > This is weird.
> > >
> > > f <- function(x) { x^2 + 2*x+1 }
> > > Df <- f
> > > body(Df) <- deriv(body(f), "x") # error
> > >
> > > Also:
> > >
> > > f <- function(x) x^2 + 2 * x + 1
> > > Df <- f
> > > body(Df) <- deriv(body(f), "x") # ok
> > > D2f <- f
> > > body(D2f) <- deriv(body(Df), "x") # error
> > >
> > > Alberto Monteiro
> > >
> >
>