refactor: Write smoothed states in GX2F (acts-project#3584)

The global chi2 fitter should write smoothed states like the other fitters since the states will contain information about previous and following measurements.

Apart from that I explicitly bound I renamed the free function `updateCovariancePredicted ` to `updateGx2fCovariance` because it is too generic for the public `Acts` namespace and bound the implementation explicitly to the namespace to avoid linker errors while renaming.

Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp

@@ -52,8 +52,8 @@ namespace Acts::Experimental {
 namespace Gx2fConstants {
 constexpr std::string_view gx2fnUpdateColumn = "Gx2fnUpdateColumn";
 
-// Mask for the track states. We don't need Smoothed and Filtered
-constexpr TrackStatePropMask trackStateMask = TrackStatePropMask::Predicted |
+// Mask for the track states. We don't need Predicted and Filtered
+constexpr TrackStatePropMask trackStateMask = TrackStatePropMask::Smoothed |
                                               TrackStatePropMask::Jacobian |
                                               TrackStatePropMask::Calibrated;
 
@@ -343,7 +343,7 @@ void addMeasurementToGx2fSums(Eigen::MatrixXd& aMatrixExtended,
     extendedJacobian.block<eBoundSize, 2>(0, deltaPosition) = jacPhiTheta;
   }
 
-  const BoundVector predicted = trackState.predicted();
+  const BoundVector predicted = trackState.smoothed();
 
   const ActsVector<kMeasDim> measurement =
       trackState.template calibrated<kMeasDim>();
@@ -431,7 +431,7 @@ void addMaterialToGx2fSums(
         "No scattering angles found for material surface.");
   }
 
-  const ActsScalar sinThetaLoc = std::sin(trackState.predicted()[eBoundTheta]);
+  const ActsScalar sinThetaLoc = std::sin(trackState.smoothed()[eBoundTheta]);
 
   // The position, where we need to insert the values in aMatrix and bVector
   const std::size_t deltaPosition = eBoundSize + 2 * nMaterialsHandled;
@@ -497,9 +497,9 @@ void addMaterialToGx2fSums(
 /// @param ndfSystem The number of degrees of freedom, determining the size of meaning full block
 ///
 /// @return deltaParams The calculated delta parameters.
-void updateCovariancePredicted(BoundMatrix& fullCovariancePredicted,
-                               Eigen::MatrixXd& aMatrixExtended,
-                               const std::size_t ndfSystem);
+void updateGx2fCovarianceParams(BoundMatrix& fullCovariancePredicted,
+                                Eigen::MatrixXd& aMatrixExtended,
+                                const std::size_t ndfSystem);
 
 /// Global Chi Square fitter (GX2F) implementation.
 ///
@@ -736,8 +736,8 @@ class Gx2Fitter {
           }
 
           // Fill the track state
-          trackStateProxy.predicted() = boundParams.parameters();
-          trackStateProxy.predictedCovariance() = state.stepping.cov;
+          trackStateProxy.smoothed() = boundParams.parameters();
+          trackStateProxy.smoothedCovariance() = state.stepping.cov;
 
           trackStateProxy.jacobian() = jacobian;
           trackStateProxy.pathLength() = pathLength;
@@ -746,13 +746,13 @@ class Gx2Fitter {
             stepper.update(state.stepping,
                            transformBoundToFreeParameters(
                                trackStateProxy.referenceSurface(),
-                               state.geoContext, trackStateProxy.predicted()),
-                           trackStateProxy.predicted(),
-                           trackStateProxy.predictedCovariance(), *surface);
+                               state.geoContext, trackStateProxy.smoothed()),
+                           trackStateProxy.smoothed(),
+                           trackStateProxy.smoothedCovariance(), *surface);
           }
         }
 
-        // We have predicted parameters, so calibrate the uncalibrated input
+        // We have smoothed parameters, so calibrate the uncalibrated input
         // measurement
         extensions.calibrator(state.geoContext, *calibrationContext,
                               sourcelink_it->second, trackStateProxy);
@@ -837,18 +837,18 @@ class Gx2Fitter {
           ACTS_VERBOSE("    boundParams after the update:\n" << boundParams);
 
           // Fill the track state
-          trackStateProxy.predicted() = boundParams.parameters();
-          trackStateProxy.predictedCovariance() = state.stepping.cov;
+          trackStateProxy.smoothed() = boundParams.parameters();
+          trackStateProxy.smoothedCovariance() = state.stepping.cov;
 
           trackStateProxy.jacobian() = jacobian;
           trackStateProxy.pathLength() = pathLength;
 
           stepper.update(state.stepping,
                          transformBoundToFreeParameters(
                              trackStateProxy.referenceSurface(),
-                             state.geoContext, trackStateProxy.predicted()),
-                         trackStateProxy.predicted(),
-                         trackStateProxy.predictedCovariance(), *surface);
+                             state.geoContext, trackStateProxy.smoothed()),
+                         trackStateProxy.smoothed(),
+                         trackStateProxy.smoothedCovariance(), *surface);
         }
 
         // Get and set the type flags
@@ -921,8 +921,8 @@ class Gx2Fitter {
           const auto& [boundParams, jacobian, pathLength] = *res;
 
           // Fill the track state
-          trackStateProxy.predicted() = boundParams.parameters();
-          trackStateProxy.predictedCovariance() = state.stepping.cov;
+          trackStateProxy.smoothed() = boundParams.parameters();
+          trackStateProxy.smoothedCovariance() = state.stepping.cov;
 
           trackStateProxy.jacobian() = jacobian;
           trackStateProxy.pathLength() = pathLength;
@@ -1334,16 +1334,16 @@ class Gx2Fitter {
         ACTS_INFO("Abort with relChi2changeCutOff after "
                   << nUpdate + 1 << "/" << gx2fOptions.nUpdateMax
                   << " iterations.");
-        updateCovariancePredicted(fullCovariancePredicted, aMatrixExtended,
-                                  ndfSystem);
+        updateGx2fCovarianceParams(fullCovariancePredicted, aMatrixExtended,
+                                   ndfSystem);
         break;
       }
 
       if (chi2sum > oldChi2sum + 1e-5) {
         ACTS_DEBUG("chi2 not converging monotonically");
 
-        updateCovariancePredicted(fullCovariancePredicted, aMatrixExtended,
-                                  ndfSystem);
+        updateGx2fCovarianceParams(fullCovariancePredicted, aMatrixExtended,
+                                   ndfSystem);
         break;
       }
 
@@ -1361,8 +1361,8 @@ class Gx2Fitter {
           return Experimental::GlobalChiSquareFitterError::DidNotConverge;
         }
 
-        updateCovariancePredicted(fullCovariancePredicted, aMatrixExtended,
-                                  ndfSystem);
+        updateGx2fCovarianceParams(fullCovariancePredicted, aMatrixExtended,
+                                   ndfSystem);
         break;
       }
 

Core/src/TrackFitting/GlobalChiSquareFitter.cpp

@@ -1,6 +1,6 @@
 // This file is part of the Acts project.
 //
-// Copyright (C) 2023 CERN for the benefit of the Acts project
+// Copyright (C) 2023-2024 CERN for the benefit of the Acts project
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -10,11 +10,9 @@
 
 #include "Acts/Definitions/TrackParametrization.hpp"
 
-namespace Acts::Experimental {
-
-void updateCovariancePredicted(BoundMatrix& fullCovariancePredicted,
-                               Eigen::MatrixXd& aMatrixExtended,
-                               const std::size_t ndfSystem) {
+void Acts::Experimental::updateGx2fCovarianceParams(
+    BoundMatrix& fullCovariancePredicted, Eigen::MatrixXd& aMatrixExtended,
+    const std::size_t ndfSystem) {
   // make invertible
   for (int i = 0; i < aMatrixExtended.rows(); ++i) {
     if (aMatrixExtended(i, i) == 0.) {
@@ -29,5 +27,3 @@ void updateCovariancePredicted(BoundMatrix& fullCovariancePredicted,
 
   return;
 }
-
-}  // namespace Acts::Experimental

Examples/Io/Root/src/RootTrackStatesWriter.cpp

@@ -486,7 +486,8 @@ ProcessCode RootTrackStatesWriter::writeT(const AlgorithmContext& ctx,
         if (ipar == eSmoothed && state.hasSmoothed()) {
           return std::make_pair(state.smoothed(), state.smoothedCovariance());
         }
-        if (ipar == eUnbiased && state.hasSmoothed() && state.hasProjector()) {
+        if (ipar == eUnbiased && state.hasSmoothed() && state.hasProjector() &&
+            state.hasCalibrated()) {
           // calculate the unbiased track parameters (i.e. fitted track
           // parameters with this measurement removed) using Eq.(12a)-Eq.(12c)
           // of NIMA 262, 444 (1987)