R help - Aug 2008 - how to draw a perspective pyramid

Dear list,

I am trying to construct a perspective plot of a 2D triangle, or pyramid.  I
can easily do the one dimensional plot (code below), but I can't figure out
how to do it in a perspective plot for two input variables.  Does anyone
have a simple solution? 

Thanks!
Derek

#code for a triangle
u <- seq(-1,1,.001)
tri <- (1-abs(u))
plot(tri~u,type="l",main="Second Iteration Kernel: Two Input
Variables",lwd=2,
	xlab="x",ylab="y",col="blue")

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On Aug 31, 2008, at 7:21 PM, dxc13 wrote:
>
> Dear list,
>
> I am trying to construct a perspective plot of a 2D triangle, or  
> pyramid.  I
> can easily do the one dimensional plot (code below), but I can't  
> figure out
> how to do it in a perspective plot for two input variables.  Does  
> anyone
> have a simple solution?
>
> Thanks!
> Derek
>
> #code for a triangle
> u <- seq(-1,1,.001)
> tri <- (1-abs(u))
> plot(tri~u,type="l",main="Second Iteration Kernel: Two Input
> Variables",lwd=2,
> 	xlab="x",ylab="y",col="blue")
You probably don't want to have quite so many points in your parameter  
variables.

This is not a correct solution, but maybe it will get you further along:

u <- seq(-1,1,.1)
  v <- seq(-1,1,.1)
  z <- outer(u,v,f)
  f <- function(u,v) { val <- 1 -abs(u) -abs(v) }
  z <- outer(u,v,f)
  persp(u,v,z, xlim = c(-2,2), phi = 30, theta=30)

For one complete solution fry ?ifelse

-- 
David Winsemius