docs

Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp

@@ -361,7 +361,22 @@ struct Gx2fSystem {
   std::size_t m_ndf = 0u;
 };
 
-// TODO write description
+/// @brief Adds a measurement to the GX2F equation system in a modular backend function.
+///
+/// This function processes measurement data and integrates it into the GX2F
+/// system.
+///
+/// @param extendedSystem All parameters of the current equation system to update.
+/// @param jacobianFromStart The Jacobian matrix from the start to the current state.
+/// @param covarianceMeasurement The covariance matrix of the measurement.
+/// @param predicted The predicted state vector based on the track state.
+/// @param measurement The measurement vector.
+/// @param projector The projection matrix.
+/// @param logger A logger instance.
+///
+/// @note The dynamic Eigen matrices are suboptimal. We could think of
+/// templating again in the future on kMeasDims. We currently use dynamic
+/// matrices to reduce the memory during compile time.
 void addMeasurementToGx2fSumsBackend(
     Gx2fSystem& extendedSystem,
     const std::vector<BoundMatrix>& jacobianFromStart,
@@ -378,7 +393,7 @@ void addMeasurementToGx2fSumsBackend(
 /// @tparam kMeasDim Number of dimensions of the measurement
 /// @tparam track_state_t The type of the track state
 ///
-/// @param extendedSystem All parameters of the current equation system
+/// @param extendedSystem All parameters of the current equation system to update
 /// @param jacobianFromStart The Jacobian matrix from start to the current state
 /// @param trackState The track state to analyse
 /// @param logger A logger instance
@@ -622,8 +637,13 @@ std::size_t countMaterialStates(
   return nMaterialSurfaces;
 }
 
-// TODO write description
-// calculate delta params [a] * delta = b
+/// @brief Solve the gx2f system to get the delta parameters for the update
+///
+/// This function computes the delta parameters for the GX2F Actor fitting
+/// process by solving the linear equation system [a] * delta = b. It uses the
+/// column-pivoting Householder QR decomposition for numerical stability.
+///
+/// @param extendedSystem All parameters of the current equation system
 Eigen::VectorXd computeGx2fDeltaParams(const Gx2fSystem& extendedSystem);
 
 /// @brief Update parameters (and scattering angles if applicable)