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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Index type for PermutationMatrix and Transpositions
- From: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>
- Date: Tue, 25 Jan 2011 10:34:05 +0100
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yes for sparse matrices we can already control the index type, and
that's also why it is important to have this IndexType parameter in
PermutationMatrix and Transpositions.
gael
On Tue, Jan 25, 2011 at 10:29 AM, Helmut Jarausch
<jarausch@xxxxxxxxxxxxxxxxxxx> wrote:
> On 01/25/11 10:11:22, Gael Guennebaud wrote:
>> Since it is unbelievable
>> that one day someone will perform a LU or LDLT dec on a matrix
>> requiring 64bits integers for the indices (think about the size of
>> the
>> matrix!), I think it is safe to use int there too.
>
> I agree for dense matrices, but a tridiagonal matrix of size 2^32
> isn't out of range (IMHO). So the situation might be different for
> sparse matrices - even in the near future.
>
> Helmut.
>
>
> --
> Helmut Jarausch
> Lehrstuhl fuer Numerische Mathematik
> RWTH - Aachen University
> D 52056 Aachen, Germany
>
>
>