how to plot an user-defined function

Your function 'll' only returns a single value when passed a vector:
x <- seq(0,2,.1)
ll(x)
[1] -7.571559

'plot' expects to pass a vector to the function and have it return a
vector of the same length; e.g.,
sin(x)
[1] 0.00000000 0.09983342 0.19866933 0.29552021 0.38941834 0.47942554
0.56464247 0.64421769 0.71735609
[10] 0.78332691 0.84147098 0.89120736 0.93203909 0.96355819 0.98544973
0.99749499 0.99957360 0.99166481
[19] 0.97384763 0.94630009 0.90929743

So you either have to rewrite your function, or have a loop that will
evaluate the function at each individual point and then plot it.
Dear R-users,

Suppose I have defined a likelihood function as ll(tau), how can I plot this
likelihood function by calling it by plot?

I want to do it like this:

ll <- function(tau)
 {
   w <- 1 / (s^2 + tau^2)
   mu <- sum(theta * w) / sum(w)
   -1/2*sum((theta-mu)^2*w -log(w))
 }
plot(ll, 0, 2)

But have the following error:
Error in xy.coords(x, y, xlabel, ylabel, log) :
 'x' and 'y' lengths differ
In addition: Warning messages:
1: In s^2 + tau^2 :
 longer object length is not a multiple of shorter object length
2: In theta * w :
 longer object length is not a multiple of shorter object length
3: In (theta - mu)^2 * w :
 longer object length is not a multiple of shorter object length

Thanks

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Jim Holtman
Cincinnati, OH
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What is the problem you are trying to solve?

how to plot an user-defined function

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