And, this is why I keep asking for more context about what you are
ultimately trying to accomplish. It might be that you're truly trying to
do something that is mathematically impossible (in which case you're out
of luck), but it could also be that we could suggest something that
would solve your ultimate goal.
(Someone mathier would also say that any random variable has to be
defined with respect to a *measure*, so selecting values without respect
to a probability distribution is also impossible ... in a different way
from sampling uniformly from values on the real line ...)
Ben Bolker
On 2025-07-28 1:23 p.m., Duncan Murdoch wrote:
As others have told you, you can't. You can talk about a uniform
distribution on the reals but there's no way to normlize it so it
integrates to 1, so it's an "improper" distribution, and there is no way
to sample from those.
Duncan Murdoch
On 2025-07-28 12:30 p.m., Daniel Lobo wrote:
Many thanks for your guidance. However my original problem is, how to
select n points in the Real line randomly without any preference of
any particular probability distribution?
On Mon, 28 Jul 2025 at 21:45, Rui Barradas <ruipbarra...@sapo.pt> wrote:
On 7/28/2025 5:00 PM, Daniel Lobo wrote:
Hi,
I want to draw a set of random number from Uniform distribution where
Support is the entire Real line.
runif(4, min = -Inf, max = Inf)
However it produces all NAN
Could you please help with the right approach?
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Hello,
What you are asking doesn't make sense.
The uniform distribution's PDF is
f(x;a, b) = 1/abs(b - a) if x in [a, b]
0 otherwise
So what you have is 1/abs(Inf - -Inf) = 1/abs(Inf) = 0.
And the cumulative distribution function is even worse, it will give you
the indeterminate Inf/Inf.
See the Wikipedia on the uniform distribution [1].
[1] https://en.wikipedia.org/wiki/Continuous_uniform_distribution
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______________________________________________
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--
Dr. Benjamin Bolker
Professor, Mathematics & Statistics and Biology, McMaster University
Director, School of Computational Science and Engineering
> E-mail is sent at my convenience; I don't expect replies outside of
working hours.
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