R help - Jul 2025 - Drawing random numbers from Uniform distribution with infinite range

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

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 <ruipbarradas at 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?
> >
> > ______________________________________________
> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
https://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> 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