[Haskell-cafe] low-cost matrix rank?

Mike Meyer mwm at mired.org
Fri Apr 24 13:30:23 UTC 2015

The bed-and-breakfast isn't to bad, except for needing TH. But it's
apparently not being maintained. I've started the process of replacing the
maintainer, but may roll my own instead.


On Fri, Apr 24, 2015 at 8:27 AM, Dennis J. McWherter, Jr. <
dennis at deathbytape.com> wrote:

> I am not aware of any small library which does just this, but you could
> easily roll your own. Though not the most efficient method, implementing
> gaussian elimination is a straightforward task (you can even find the
> backtracking algorithm on google) and then you can find the rank from there.
> Dennis
> On Fri, Apr 24, 2015 at 6:50 AM, Mike Meyer <mwm at mired.org> wrote:
>> My apologies,but my use of "low-cost" was ambiguous.
>> I meant the cost of having it available - installation, size of the
>> package, extra packages brought in, etc. I don't the rank calculation to be
>> fast, or even cheap to compute, as it's not used very often, and not for
>> very large matrices. I'd rather not have the size of the software
>> multiplied by integers in order to get that one function.
>> hmatrix is highly optimized for performance and parallelization, built on
>> top of a large C libraries with lots of functionality. Nice to have if
>> you're doing any serious work with matrices, but massive overkill for what
>> I need.
>> On Fri, Apr 24, 2015 at 3:13 AM, Alberto Ruiz <aruiz at um.es> wrote:
>>> Hi Mike,
>>> If you need a robust numerical computation you can try "rcond" or "rank"
>>> from hmatrix. (It is based on the singular values, I don't know if the cost
>>> is low enough for your application.)
>>> http://en.wikipedia.org/wiki/Rank_%28linear_algebra%29#Computation
>>> https://hackage.haskell.org/package/hmatrix-
>>> Alberto
>>> On 24/04/15 00:34, Mike Meyer wrote:
>>>> Noticing that diagrams 1.3 has moved from vector-space to linear, I
>>>> decided to check them both for a function to compute the rank of a
>>>> matrix. Neither seems to have it.
>>>> While I'm doing quite a bit of work with 2 and 3-element vectors, the
>>>> only thing I do with matrices is take their rank, as part of verifying
>>>> that the faces of a polyhedron actually make a polyhedron.
>>>> So I'm looking for a relatively light-weight way of doing so that will
>>>> work with a recent (7.8 or 7.10) ghc release. Or maybe getting such a
>>>> function added to an existing library. Anyone have any suggestions?
>>>> Thanks,
>>>> Mike
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