Re: [eigen] Problem with LU and Cholesky inversion

[Benoît Jacob <jacob@xxxxxxxxxxxxxxx>]

The spamming continues...

The LU::solve() actually does evaluate its argument b into a matrix c and uses 
only c from that point on... in particular it calls solveTriangular on c 
only... so I really don't understand why it has trouble.

Moreover I added this test in test/lu.cpp:

  // unit-test for a bad bug that escaped us for a long time:
  // make sure that LU::solve() works well when passed an expression
  m4 = (m1*m2).transpose();
  lu.solve(m4.transpose(), &m2);
  VERIFY_IS_APPROX(m4.transpose(), m1*m2);

This test succeeds ! This is strange as it seems the same as Timothy's code 
which makes LU::solve() fail.

I'm puzzled!
Benoit


On Friday 10 October 2008 15:20:21 Benoît Jacob wrote:
> Hm I read too fast: indeed we also have the same problem in LU.... which is
> my baby i.e. my fault.
>
> Still not decided whether the right approach is to evaluate or to
> nest-by-value...
>
> Cheers,
> Benoit
>
> On Friday 10 October 2008 15:04:01 Benoît Jacob wrote:
> > On Friday 10 October 2008 14:58:18 Benoît Jacob wrote:
> > > Did you forget a nestByValue() ?
> >
> > Replying to myself: hm, rather a .eval() of course as a solver typically
> > uses each coeff many times.
> >
> > By the way: the solve() API in Cholesky is not homogeneous with the other
> > solvers, it returns by value while the other solvers have a C-style API.
> > Can you harmonize that by the way?
> >
> > Cheers,
> > Benoit
> >
> > ---
>
> ---



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