On 2020-03-26 4:02 a.m., Martin Maechler wrote:
>> Ben Bolker
>> on Wed, 25 Mar 2020 21:09:16 -0400 writes:
>
> > I've discovered an infelicity (I guess) in qbeta(): it's not a bug,
> > since there's a clear warning about lack of convergence of the numerical
> >
___
> From: R-devel on behalf of J C Nash
> Sent: Thursday, March 26, 2020 10:40:05 AM
> To: Martin Maechler
> Cc: r-devel@r-project.org
> Subject: Re: [Rd] unstable corner of parameter space for qbeta?
> Despite the need to focus on pbeta, I'm still willi
: r-devel@r-project.org
Subject: Re: [Rd] unstable corner of parameter space for qbeta?
Despite the need to focus on pbeta, I'm still willing to put in some effort.
But I find it really helps to have 2-3 others involved, since the questions back
and forth keep matters moving forward. Volunte
Despite the need to focus on pbeta, I'm still willing to put in some effort.
But I find it really helps to have 2-3 others involved, since the questions back
and forth keep matters moving forward. Volunteers?
Thanks to Martin for detailed comments.
JN
On 2020-03-26 10:34 a.m., Martin Maechler
> J C Nash
> on Thu, 26 Mar 2020 09:29:53 -0400 writes:
> Given that a number of us are housebound, it might be a good time to try
to
> improve the approximation. It's not an area where I have much expertise,
but in
> looking at the qbeta.c code I see a lot of
Given that a number of us are housebound, it might be a good time to try to
improve the approximation. It's not an area where I have much expertise, but in
looking at the qbeta.c code I see a lot of root-finding, where I do have some
background. However, I'm very reluctant to work alone on this,
It's a pretty extreme case, try e.g. curve(pbeta(x, shape1, shape2), n=10001),
and (probably -- I can't be bothered to work out the relation between beta
shapes and F df parameters this morning...) outside what is normally
encountered in statistical analyses. Notice though, that you have
> Ben Bolker
> on Wed, 25 Mar 2020 21:09:16 -0400 writes:
> I've discovered an infelicity (I guess) in qbeta(): it's not a bug,
> since there's a clear warning about lack of convergence of the numerical
> algorithm ("full precision may not have been achieved"). I can
I've discovered an infelicity (I guess) in qbeta(): it's not a bug,
since there's a clear warning about lack of convergence of the numerical
algorithm ("full precision may not have been achieved"). I can work
around this, but I'm curious why it happens and whether there's a better
workaround
