| Re: [eigen] [patch] LDLt decomposition with rank-deficient matrices |
[ Thread Index |
Date Index
| More lists.tuxfamily.org/eigen Archives
]
- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] [patch] LDLt decomposition with rank-deficient matrices
- From: Ben Goodrich <bgokgm@xxxxxxxxxxxxxx>
- Date: Mon, 28 Jun 2010 18:55:08 -0400
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=mWtL1iGDLAxW9b1fSdY4JjMg8x0EU8sq6XPX3C6C98k=; b=rqDY3vR0etPXbHpj8oi3Kho58L+XV+13legaFtdkztxVhT4QWYAit2TUlpfi3WvM4R fb+Dhxb9BgFAFDCE52XM6c3xaBiuF6zFXF/m3Kff6ObiYM7Qh4kp6iH34NIN/Ty6by+G 9mdJoOhD0Nna0aIlqu+FHnTD+dM5v6gZdy8YY=
- Domainkey-signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=pyjfGD/UPowq1LgTUi1VrGGx6oR/xIoRDY3aW2KUpgOxqyRGW3oRKAyDwcKDxwsfe9 wkTZYGcnoATUqcxaxVmtLm0bO060Zhja5KP2rPZuqmT8iM7JoYXUvDDaBEBoN0/4U1N9 PGYTWCGkPLjSkXhdDix51r6cz8cdMPeHVkrwA=
Hi Manoj,
On Mon, Jun 28, 2010 at 6:49 PM, Manoj Rajagopalan <rmanoj@xxxxxxxxx> wrote:
>
>
>
> On Monday 28 June 2010 02:00:50 pm Ben Goodrich wrote:
>> Hi Benoit,
>>
>> On Mon, Jun 28, 2010 at 8:51 AM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
> wrote:
>> > Hi Ben,
>> >
>> > Let's get this sorted :) So far I didn't participate much in the
>> > discussion so I may be missing a lot of things.
>> >
>> > When it was question of making pivoting/nopivoting an option of the
>> > LDLT class, I thought we were talking about a template parameter. If
>> > fact, in your patch, it is a runtime option. In all other
>> > decompositions in Eigen, we have made this be separate classes, e.g.
>> > HouseholderQR vs ColPivHouseholderQR. Frankly I would like LDLT to do
>> > the same. Keep LDLT pivoting, and add a NoPivLDLT class. This will
>> > actually make your NoPivLDLT be more optimized (the biggest advantage
>> > will be smaller executable code). The only advantage of having that as
>> > runtime param is to share code if a user is using both flavors of
>> > LDLT. I believe that the most common case is that a program will use
>> > at most one flavor of LDLT.
>> >
>> > If you send a patch with this change, I promise I'll review it :)
>> >
>> > Benoit
>>
>> That is all fine with me; I don't have any strong reason to prefer a
>> runtime option. But I interpreted Gael's email on June 16 as asking
>> for a runtime option and then later he asked about the possibly of a
>> separate class. So, it seems we now have a consensus on the separate
>> class at least. :)
>>
>> Ben
>>
>
>
> Would it make sense to add an extra boolean template parameter to the LDLT
> template that defaults to 'true' with 'false' being the no-pivot case? Since
> partial specialization is allowed with class templates this should cause no
> problems with existing code that uses LDLT, AFAIK ...
>
> -- Manoj
That would work fine, but rather than booleans, Gael (and others, I
think) prefer
int options = Pivoting
where Pivoting is already mapped to some integer in
Eigen/src/Core/util/Constants.h .
Ben