Re: [eigen] [FAQ] how to have an initialized static Matrix

[Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>]

On 21.03.2013 11:54, Helmut Jarausch wrote:
> On 03/21/2013 11:44:14 AM, Christoph Hertzberg wrote:
> > I found another very hacked solution. It requires that the data layout
> > of Matrix will not change (especially, no extra fields will be
> > introduced):
> >
> > EIGEN_ALIGN16
> > static const double C3_data[] = {1.0/5, 3.0/10, 4.0/5, 8.0/9, 1.0, 1..0};
> > static const Vec6d& C3 = reinterpret_cast<const Vec6d&>(*C3_data);
>
> That's the case for my application : matrix and vectors of weights in
> higher order Runge-Kutta methods.

What I meant was that Eigen's internal structure must not change (which 
should be the case for basic data types at least for Eigen 3.x

> Still, for a "real" matrix one would have to enter the transposed matrix
> if one likes to stay to
> column ordering for efficiency.

You can declare all your matrices as row-major, you have an overhead 
only for operations where you mix column ordering, I don't think 
col-major is generally superior to row-major.

Christoph

--
----------------------------------------------
Dipl.-Inf., Dipl.-Math. Christoph Hertzberg
Cartesium 0.049
Universität Bremen
Enrique-Schmidt-Straße 5
28359 Bremen

Tel: +49 (421) 218-64252
----------------------------------------------