On 04/07/2009 3:31 PM, Hao Jiang wrote:
Hi Duncan,Thanks!
But I still get a little confused about outer() func. Would give me a simple
example to contour it? Just like the formula x^2 + y^2 + x + y -5 = 0.
(Sorry I am a newbie to R, found really hard to use the R manual)
> x <- seq(-6,6,len=100)
> y <- seq(-4,4,len=100)
> z <- outer(x,y, function(x,y) x^2 + y^2 + x + y -5)
> contour(x,y,z,levels=0)
This will draw a contour of the solutions to the equation. (I set the
ranges of x and y differently just so I could be sure I got them in the
right order in the outer and contour functions.)
Duncan Murdoch
Thanks,
Hao
On Sat, Jul 4, 2009 at 7:10 AM, Duncan Murdoch <murd...@stats.uwo.ca> wrote:
Hao Jiang wrote:
Hi,
I want to plot a polynomial in the form like ax^2 + bxy + cy^2 + dx + ey +
f
=0 without solving it(since I may have 3 or 4 dimensional polynomial and
it's really hard to solve). Is there any way to plot this kind of
polynomial?
Thanks a lot!
There are lots of ways. A contour plot is probably most informative, a
persp plot is prettier. In either case you need to evaluate the polynomial
on a grid, and pass the matrix of values to the plotting function.
The outer() function is handy for doing the grid evaluation.
Duncan Murdoch
______________________________________________
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.
