I accidentally did not respond to the list.

---------- Forwarded message ----------
From: Abhilash Balakrishnan <balaabhil@gmail.com>
Date: Sun, Jun 5, 2011 at 8:44 PM
Subject: Re: [R] Question about curve function
To: Matt Shotwell <matt@biostatmatt.com>


Dear Mr. Shotwell,

Thank you for the explanation.  You seem to be right.  In particular I tried
the following:

> x <- function(x) { x }
> curve(x)
Works!  So, now x is interpreted as a function, and is plotted accordingly.
 I also found that this works too:

> curve(I)
With your explanation I now understand why it works.

Thank you for support.
Abhilash B.


On Sun, Jun 5, 2011 at 1:11 PM, Matt Shotwell <matt@biostatmatt.com> wrote:

> I think there is trouble because expr in curve(expr) may be the name of
> a function, and it's ambiguous whether 'x' should be interpreted as a
> mathematical expression involving x, or the name of a function. Here are
> some examples that work:
>
> curve(I(x))
> curve(1*x)
>
> On Sun, 2011-06-05 at 12:07 -0500, Abhilash Balakrishnan wrote:
> > Dear Sirs,
> >
> > I am a new user of the R package.  When I try to use the curve function
> it
> > confuses me.
> >
> > > curve(x^2)
> > Works fine.
> >
> > > curve(x)
> > Makes a complaint I don't understand.  Why is x^2 valid and x is not?
> >
> > I check the documentation of curve, and it says the first argument must
> be
> > an expression containing x.
> >
> > > expression(x)
> > Is an expression containing x.
> >
> > > curve(expression(x))
> > Makes a different complaint and mentions different lengths of x and y
> (but I
> > use no y here).
> >
> > I understand that plotting the function y(x) = x is rather silly, but I
> want
> > to know what I am doing wrong, for the sake of my understanding of how R
> > works.
> >
> > Thank you for support.
> > Abhilash B.
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > 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.
>
>
>

	[[alternative HTML version deleted]]

