print Eigen matrix of type T in operator()

[phreak...@gmail.com]

Hi, I'm trying to debug my cost function and would like to print intermediate values to console. I'm using Eigen to wrap the pointer-to-T arrays as Eigen matrices of type T, thus I'm doing:

std::cout << residual << std::endl;

where residual is of type Eigen::Matrix<T,3,1>. However, I'm getting: 

/usr/include/eigen3/Eigen/src/Core/MathFunctions.h:365:34: error: invalid static_cast from type ‘const ceres::Jet<double, 13>’ to type ‘int’

     return static_cast<NewType>(x);

It would seem that Eigen is trying to cast the elements to numbers for display and thus it does not call the stream operator directly on its elements (which I assume is implemented on ceres side). How could I print my residual in this case?

Best,

Matias

[Alex Stewart]

There should be no issues streaming matrices of Jets - updating the example helloworld.cc for example to:

struct CostFunctor {

  template <typename T> bool operator()(const T* const x, T* residual) const {

    residual[0] = 10.0 - x[0];

    std::cerr << "Residual: " << Eigen::Map<Eigen::Matrix<T, 1, 1> >(residual) << std::endl;

    return true;

  }

};

produces the expected output of the form:

Residual:          [9.5 ; -1]

when T is a Jet.  What is the callstack for this error?  And what version of Ceres & Eigen are you using?

-Alex

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[phreak...@gmail.com]

Hi,

I think the problem was that I had a Ref to a Matrix, not a Matrix itself.