operator().cpp

// Compute 'm' errors, one for each data point, for the given parameter values in 'x'
int operator()(const Eigen::VectorXf &x, Eigen::VectorXf &fvec) const
{
    // 'x' has dimensions n x 1
    // It contains the current estimates for the parameters.

    // 'fvec' has dimensions m x 1
    // It will contain the error for each data point.

    float aParam = x(0);
    float bParam = x(1);
    float cParam = x(2);

    for (int i = 0; i < values(); i++) {
        float xValue = measuredValues(i, 0);
        float yValue = measuredValues(i, 1);

        fvec(i) = yValue - (aParam * xValue * xValue + bParam * xValue + cParam);
    }
    
    return 0;
}