R help - Jan 2008 - Ryacas

I'm tinkering around in Ryacas trying to find an easy way to get the
first and second partial derivatives of mu and sigma from a normal
distribution (actually a bitterly ugly likelihood but this example works
for now). 

I've done all of the work in Mathematica, but I then need to manually
write R code whereas I think Ryacas will give me the expression such
that I can export for Tex and produce code I can use for a function. Is
there a way I can use Ryacas with built in functions, like dnorm?

For example, I can define the normal and then use the D function as:

ndist<-expression( (1/(s*sqrt(2*pi)))  * exp(- ((x-u)^2/(2*s^2))))
D(ndist, "u")

But, I don't see in the vignette a way to use dnorm?

You can only use those functions that Ryacas knows about
or that Yacas 1.0.63 knows about:

library(Ryacas)
View(transtab)

and

ls("package:Ryacas")

The Ryacas home page http://ryacas.googlecode.com
has links to the yacas home page.

Sometimes using the first few terms of the Taylor representation is
sufficient workaround.

On Jan 31, 2008 12:01 PM, Doran, Harold <HDoran at air.org>
wrote:
> I'm tinkering around in Ryacas trying to find an easy way to get the
> first and second partial derivatives of mu and sigma from a normal
> distribution (actually a bitterly ugly likelihood but this example works
> for now).
>
> I've done all of the work in Mathematica, but I then need to manually
> write R code whereas I think Ryacas will give me the expression such
> that I can export for Tex and produce code I can use for a function. Is
> there a way I can use Ryacas with built in functions, like dnorm?
>
> For example, I can define the normal and then use the D function as:
>
> ndist<-expression( (1/(s*sqrt(2*pi)))  * exp(- ((x-u)^2/(2*s^2))))
> D(ndist, "u")
>
> But, I don't see in the vignette a way to use dnorm?
>
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