Hello all,
I'm trying to write some code that needs to multiply two Rotation2D<float> variables and store the result in another Rotation2D<float>. A sample piece of code is

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    Eigen::Rotation2D<float> r1;                                               
    Eigen::Rotation2D<float> r2;                                               
    Eigen::Rotation2D<float> r3;                                               
    r3=r1*r2;   


However, compiling this results in the error

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./Eigen/src/Geometry/Rotation2D.h:78:28: error: could not convert ‘(((Eigen::Rotation2D<float>::Scalar)((const Eigen::Rotation2D<float>*)this)->Eigen::Rotation2D<float>::m_angle) + ((Eigen::Rotation2D<float>::Scalar)other.Eigen::Rotation2D<float>::m_angle))’ from ‘Eigen::Rotation2D<float>::Scalar {aka float}’ to ‘Eigen::Rotation2D<float>’
   { return m_angle + other.m_angle; }


Note that if you replace the Rotation2Ds with Quaternions, the code compiles without issue. Is this a bug, or am I doing something incorrect?

Thanks,
-Avi

Works for me with Eigen 3.2.3 and the devel branch. I did not check with older versions.

That's odd, I just downloaded 3.2.3 and tested it and get the same error. Could it be a g++ version issue? I've tried it with g++ 4.8.2 and 4.6. The command I'm running is

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g++ -I. test.cpp

from within the top level of the Eigen directory, and the full contents of test.cpp are

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#include <Eigen/Geometry>

int main()
{
    Eigen::Rotation2D<float> r1;                                               
    Eigen::Rotation2D<float> r2;                                               
    Eigen::Rotation2D<float> r3;                                               
    r3=r1*r2;   
    return 0;
}


Regards,
-Avi

Works for me with GCC 4.6, 4.7, 4.8, 4.9 and clang. Make sure that you are really using Eigen 3.2 and not a system-wide installed version with -I path/to/eigen3.2

I think I may see what's going on. In the 3.2.3 version available for download, the function "operator*" for Rotation2D is defined as follows:

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  inline Rotation2D operator*(const Rotation2D& other) const
  { return m_angle + other.m_angle; }


This definition won't work for my example, because the constructor that takes a Scalar as the parameter is defined as "explicit". However, in the current development source that same function is defined as

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  inline Rotation2D operator*(const Rotation2D& other) const
  { return Rotation2D(m_angle + other.m_angle); }


which does indeed work. Thank you for looking into this!

-Avi

arf, right. this has been fixed just after the 3.2.3 release, and I only tested with the 3.2 branch, not the exact 3.2.3 release. (changeset 5d9e54445535).