Re: [eigen] Re: recent improvements in the products

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

On Tue, Jul 28, 2009 at 8:24 AM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
> > * currently we can only solve for  X = M^1 * Y, but we also need X = Y *
> > M^-1. Implementation wise we just have to transpose everything, so actually,
> > the user can probably already do:
> >    m1.transpose().triangularView<UpperTriangular>(m2.transpose());
> >  but that's not very nice API wise. The only solution I see is to add an
> > option to TriangularView::solveInPlace(), e.g., solveInPlace(m2, Right);
>
> Yes and then i'd call that OnTheRight.

ok, finally it turns out that this "side" parameter should be a
compile time parameter, otherwise we would have:

if(side==OnTheRight)
 call version_1
else
 call version_2

that means for a template library twice the compilation time. So:
1 - it could be a template parameter of the solve function with
overloads for mimic a default parameter:

    m.triangularView<UnitUpperTriangular>().solveInPlace<OnTheRight>(x);

2 - or we can add new solve functions:

    m.triangularView<UnitUpperTriangular>().solveInPlaceOnTheRight(x);

3 - or we can define OnTheRight/OnTheLeft as instances of different
types allowing:

    m.triangularView<UnitUpperTriangular>().solveInPlace(x, OnTheRight);


any preference ?

cheers,
Gael.