Eigen C++ Assertion Failed

Question

I have an Eigen MatrixXd object, called v, and I am facing some problems when trying to access this matrix content. When I only print the content at the console (as in the code), works just as fine. When I try to use the content, the error shows up:

Assertion failed: (row >= 0 && row < rows() && col >= 0 && col < cols()), function operator(), file /usr/local/Cellar/eigen/3.2.4/include/eigen3/Eigen/src/Core/DenseCoeffsBase.h, line 337.

    ChosenPoint ** points = new ChosenPoint*[width];
    for (int i = 0; i < width; i++)
    {
        points[i] = new ChosenPoint[height];
        for (int j = 0; j < height; j++)
        {
            points[i][j].setPoint(i, j, false);
            points[i][j].setNumberOfFrames(numberOfFrames);
        }
    }

Matrix<double, 2, 1> v = (aT * a).inverse() * aT * b;
if (v.rows() == 2 && v.cols() == 1)
{
     points[x][y].setFlow(v(0,0), v(1,0), frame);
}

And my ChosenPoint class:

typedef struct point
{
    double x;
    double y;
    bool isValid;
 } point;

 class ChosenPoint 
{
public: 
ChosenPoint()
{

}

~ChosenPoint()
{
}

void setNumberOfFrames(int numberOfFrames)
{
    this->flow = new point[numberOfFrames];

    for (int i = 0; i < numberOfFrames; i++)
    {
        point f;
        f.x = 0.0;
        f.y = 0.0;
        this->flow[i] = f;
    }
}

void setPoint(int x, int y, bool isValid)
{
    this->pt.x = (double) x;
    this->pt.y = (double) y;
    this->pt.isValid = isValid;
}

point getPoint()
{
    return this->pt;
}

point* getFlow()
{
    return this->flow;
}

void setFlow(double &xFlow, double &yFlow, int &position)
{
    this->flow[position].x = xFlow;
    this->flow[position].y = yFlow;
}

void updateFlow(int position)
{
    this->flow[position].x = 2*this->flow[position].x;
    this->flow[position].y = 2*this->flow[position].y;
}

void updateFlow(double xFlow, double yFlow, int position)
{
    this->flow[position].x = xFlow;
    this->flow[position].y = yFlow;
}

point pt;
point *flow;

};

Answer 1

My fault. The problem was with one of the other matrixes that I was using in the project, and took me a while to figure it out. Unfortunately, Eigen doesn`t seem to be really helpful when this happens:

I had 2 matrixes (A and B). The matrix with problem was A (somehow, some data was not loaded into the matrix). But when i multiplied A and B, it generated a new matrix C with some valid results (all my sanity checks were unuseful). I admit I don`t know a lot of Eigen.

Anyway, hope this is helpful for more people like me.