Re: [eigen] new API for Cholmod |

[ Thread Index | Date Index | More lists.tuxfamily.org/eigen Archives ]

*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] new API for Cholmod*From*: Rodney Sparapani <rsparapa@xxxxxxx>*Date*: Thu, 04 Nov 2010 13:23:31 -0500

On 11/ 4/10 01:10 PM, Bill Greene wrote:

1. The ordering algorithm in a particular sparse matrix packageis likely to be useful with other sparse matrix factoring routines(i.e.the CSparse AMD would be useful with MUMPS or SPOOLES, etc.)The Metis ordering package is often very effective and isdistributed orrecommended in several sparse matrix packages-- probably all sparse backends would find this useful. 2. Users who are particularly interested in performance, often like to experiment with different ordering algorithms to find the optimum one for their problem. So its probably better to allow the user to separate the ordering step from the analysis and factorization steps.

Excellent points.

>This still require some work to make it compatible with any Eigen's >sparse representation (SparseMatrix, DynamicSparseMatrix, row-column >major, with only the lower, or upper or both triangular part etc.). Yes, I can see how this would be quite a bit of work. Did you consider just stopping with an error message if the matrix is not a SparseMatrix in the correct form-- the upper triangle for CSparse? As a user I don't think that would be so objectionable. I could then choose to convert the matrix to the correct format, myself, possibly avoiding the memory cost of having two copies of the matrix.

Definitely. CHOLMOD is a brilliant piece of software. But, one thing that has caught me with my pants down is that it will silently translate your problem into AA' if you forget to tell it that A is symmetric (and why is that anyways, then isn't the answer just A?). Let's not have any of that. -- Rodney Sparapani Center for Patient Care and Outcomes Research Sr. Biostatistician http://www.mcw.edu/pcor 4 wheels good, 2 wheels better! Medical College of Wisconsin (MCW) WWLD?: What Would Lombardi Do? Milwaukee, WI, USA

**Follow-Ups**:**Re: [eigen] new API for Cholmod***From:*Christoph Hertzberg

**References**:**Re: [eigen] new API for Cholmod***From:*Gael Guennebaud

**Re: [eigen] new API for Cholmod***From:*Bill Greene

**Messages sorted by:**[ date | thread ]- Prev by Date:
**Re: [eigen] Build Failure** - Next by Date:
**Re: [eigen] new API for Cholmod** - Previous by thread:
**Re: [eigen] new API for Cholmod** - Next by thread:
**Re: [eigen] new API for Cholmod**

Mail converted by MHonArc 2.6.19+ | http://listengine.tuxfamily.org/ |