[Haskell-cafe] low-cost matrix rank?

[Dennis J. McWherter, Jr.]

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-0.16.1.5/docs/Numeric-LinearAlgebra-HMatrix.html#g:10
>>
>> 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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