Re: [eigen] eigen 3.3.1 upgrade

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

This is an aliasing issue. Looks like mP.triangularView<Upper>() assumes no aliasing by default and the generated code looks like:

1: mP.triangularView<Upper>().setZero();

2: tmp = mPHI * mP.selfadjointView<Upper>();

3: mP.triangularView<Upper>() += tmp * mPHI.adjoint();

I'll see if the setZero can be deferred a bit more.

gael

On Tue, Jan 17, 2017 at 5:16 AM, William Lentz <william_lentz@xxxxxxxxxxx> wrote:

Hi,

I'm trying to upgrade to Eigen 3.3..1 and ran into a problem.  The following code produces an all-0 matrix with the "#if 1" and produces the identity matrix if changed to "#if 0".  I'm using gcc 4.8.5 and compiling as "g++ -O -I eigen-eigen-f562a193118d/Eigen test.cpp"

#include <iostream>

#include "Eigen"

using namespace Eigen;

using namespace std;

int main(void)

{

  MatrixXd mP = MatrixXd::Identity(3,3) ;

  MatrixXd mPHI = MatrixXd::Identity(3,3) ;

#if 1

  mP.triangularView<Upper>() = mPHI *

                               mP.selfadjointView<Upper>() *

                               mPHI.adjoint();

#else

  mP = mPHI *

       mP.selfadjointView<Upper>() *

       mPHI.adjoint();

#endif

  cout << mP << endl ;

  return 0 ;

}

An older version of Eigen from 2014 produces the identity matrix either way.  Any ideas?

Thanks,

Will