R help - Apr 2007 - How to find a uniroot of a deriv function

Hi, All

Assume I have function x^2-1, I tried to find the root of its derivative
2*x = 0.

I run the command below but it return 1, root of the original function.
Does anyone know how to get the root of the derived function?

Thanks
pat
=======================================func =
deriv(parse(text="x^2-1"), "x", func=TRUE)
uniroot(func, interval=(-0.1,1.1), tol=1e-6)
=======================$root
[1] 1

$f.root
[1] -1.709702e-07
attr(,"gradient")
     x
[1,] 2

Try this:


func <- function(x) {}
body(func) <- D(quote(x^2-1), "x")
uniroot(func, interval=c(-0.1,1.1), tol=1e-6)


On 4/13/07, Patrick Wang <pwang at berkeley.edu>
wrote:
> Hi, All
>
> Assume I have function x^2-1, I tried to find the root of its derivative
> 2*x = 0.
>
> I run the command below but it return 1, root of the original function.
> Does anyone know how to get the root of the derived function?
>
> Thanks
> pat
> =======================================> func =
deriv(parse(text="x^2-1"), "x", func=TRUE)
> uniroot(func, interval=(-0.1,1.1), tol=1e-6)
> =======================> $root
> [1] 1
>
> $f.root
> [1] -1.709702e-07
> attr(,"gradient")
>     x
> [1,] 2
>
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