On Mar 28, 2010, at 3:19 AM, Severin Kacianka wrote:
Hello,
I try to create a persp-plot for the bivariate normal distribution.
There are a few solutions online ([1],[2]), but I did not want to
hard-code the formula like [2] did or use a kernel density estimate
like [1].
My plan was to use dmvnorm, and use outer to calculate the z-
dimension for each point. Here is what I tried:
library(mvtnorm)
x<-seq(0,1,len=40)
y<-x
g<-function(a,b) {
dmvnorm(x=c(a,b))
The construction "c(a,b)" would in the later function call turn those
two 40 element vectors into an 80 element vector. See if you get
better success with cbind.
}
z<-outer(x,y,g)
Which results in the following error:
Error in dim(robj) <- c(dX, dY) :
dims [product 1600] do not match the length of object [1]
What causes this error? If I set g to be a simple function like:
g<-function(a,b){
a*b
}
Everything works fine. Why does it fail when I pass the parameters
to dmvnorm?
Thank you for your time,
Severin
[1]https://stat.ethz.ch/pipermail/r-help/2003-September/038314.html
[2]http://www.stat.ucl.ac.be/ISpersonnel/lecoutre/stats/fichiers/_gallery.pdf
David Winsemius, MD
West Hartford, CT
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