[R] How to draw the graph of f(x,y) = x * y ?

[Paul Smith]

On Wed, Sep 24, 2008 at 4:05 AM, Ben Bolker <bolker at ufl.edu> wrote:
>> The function curve() draws the graph of functions from R to R. Is
>> there some homologous function to curve() to draw functions from R^2
>> to R?
>
>  There is a curve3d function in the emdbook package on CRAN.

Thanks, Ben and Robin. I think curve3d should be included in the base
of R. It would help many users, I believe.

I do not know whether curve3d could be extended to draw constant
functions and functions like f(x,y) = x. With the current version, I
get the following:

> curve3d(1)
Error in curve3d(1) :
  'expr' must be a function or an expression containing 'x' and 'y'
> curve3d(x)
Error in eval(expr, envir, enclos) : could not find function "x"
>

Paul