[R] Question about curve function

[Duncan Murdoch]

On 11-06-05 1:07 PM, 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?

curve() is a convenience function, and it tries to guess what you mean. 
  Sometimes it gets it wrong.

In the first case, it is clear you want to graph x^2.  In the second it 
guesses you have a function named x and want to graph that.  You don't, 
so it fails.

Probably it could try again after the first failure, but I'd guess there 
will always be strange cases where it does weird things.

Duncan Murdoch

>
> 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.
>
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>
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