[R] help with likelihood contour plot
Sundar Dorai-Raj
sundar.dorai-raj at pdf.com
Mon Mar 17 23:29:34 CET 2003
Murray Jorgensen wrote:
> Can some kind person point out my error here? I'm trying to set up a
> grid for a countour plot of a likelihood function.
>
> > u <- rnorm(20,9.5,2.5)
> > # sample of size 20 from N(9.5,2.5^2)
> > loglik <- function(th1,th2) {
> + n <- length(u)
> + -(n/2)*log(2*pi*th2^2)-0.5*sum((u-th1)^2/th2^2)
> + }
> > x <- seq(4.5,14.5,len=50)
> > y <- seq(0.5,6,len=50)
> > f <- outer(x, y, loglik(x,y))
> Error in match.fun(FUN) : not function, character, or symbol: "loglik(x,
> y)"
> In addition: Warning message:
> longer object length
> is not a multiple of shorter object length in: u - th1
> > loglik(9,2)
> [1] -44.56294
> > is.function(loglik)
> [1] TRUE
>
> Thanks,
>
> Murray
Murray,
From ?outer:
Details:
`FUN' must be a function (or the name of it) which expects at
least two arguments and which operates elementwise on arrays.
Thus, use "loglik" and not "loglik(x,y)", as in:
outer(x,y,loglik)
Regards,
Sundar
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