Re: [eigen] Eigen 3.0-beta1 operator+= problem

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

thank you for the self-contained test case. problem solved with
respective unit tests.

gael

On Mon, Sep 6, 2010 at 12:42 AM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
> Problem confirmed with current development branch.
>
> gdb tells me it's picking up the operator+= defined at
> Eigen/src/Core/CwiseBinaryOp.h:232:
>
> template<typename Derived>
> template<typename OtherDerived>
> EIGEN_STRONG_INLINE Derived &
> MatrixBase<Derived>::operator+=(const MatrixBase<OtherDerived>& other)
> {
>  SelfCwiseBinaryOp<ei_scalar_sum_op<Scalar>, Derived, OtherDerived>
> tmp(derived());
>  tmp = other.derived();
>  return derived();
> }
>
> So this is likely a bug in SelfCwiseBinaryOp. That's all I can do for today...
>
> Benoit
>
> 2010/9/5 Gavin Band <gavin.band@xxxxxxxxxxxxx>:
>> Dear Eigen list,
>>
>> I decided to evaluate Eigen and (wanting to dive in at the deep end) downloaded Eigen 3.0 beta.  However, I immediately ran into the problem exemplified by the code below, in which using operator+= seems to give a different answer than using operators + and = separately when the rhs is the result of ColPivHouseholderQR::solve().  (The problem did not occur with a plain MatrixXd on the right.)  Is this behaviour a bug, or am I doing something wrong?
>>
>> Many thanks,
>> Gavin Band.
>>
>> // ==== begin code ====
>>
>> #include <iostream>
>> #include <Eigen/Dense>
>>
>> int main()
>> {
>>    Eigen::VectorXd pt( 1 ), v1( 1 ), v2( 1 ) ;
>>    pt << 1 ;
>>    v1 << 1 ;
>>    v2 << 1 ;
>>
>>    Eigen::MatrixXd M( 1, 1 ) ;
>>    M << 1.0 ;
>>
>>    Eigen::ColPivHouseholderQR< Eigen::MatrixXd > decomposer( M ) ;
>>
>>    v1 += decomposer.solve( pt ) ;      //  value is 1 ???
>>    v2 = v2 + decomposer.solve( pt ) ;  //  value is 2, ok.
>>
>>    std::cerr << "QR = " << decomposer.matrixQR() << ", v1 = " << v1 << ", v2 = " << v2 << ".\n" ;
>> }
>>
>>
>>
>>
>>
>
>
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