From 8d08065533eb9d44f30cd7ffd2117ff8f2609687 Mon Sep 17 00:00:00 2001
From: christos <christos@cern.ch>
Date: Fri, 2 Dec 2022 02:51:24 +0100
Subject: [PATCH] MultiComponentStateCombiner add a comment a re-arrange a bit
the calculations
---
.../src/MultiComponentStateCombiner.cxx | 43 +++++++++++--------
1 file changed, 24 insertions(+), 19 deletions(-)
diff --git a/Tracking/TrkFitter/TrkGaussianSumFilterUtils/src/MultiComponentStateCombiner.cxx b/Tracking/TrkFitter/TrkGaussianSumFilterUtils/src/MultiComponentStateCombiner.cxx
index 5e8ba142084b..b7eafa9ebdfb 100644
--- a/Tracking/TrkFitter/TrkGaussianSumFilterUtils/src/MultiComponentStateCombiner.cxx
+++ b/Tracking/TrkFitter/TrkGaussianSumFilterUtils/src/MultiComponentStateCombiner.cxx
@@ -72,11 +72,12 @@ computeImpl(const Trk::MultiComponentState* uncombinedState,
AmgVector(5) parameters = trackParameters->parameters();
+ // Ensure that we don't have any problems with the cyclical nature of phi
+ // Use first state as reference poin
// Ensure that we don't have any problems with the cyclical nature of phi
// Use first state as reference poin
double deltaPhi =
- (*uncombinedState->begin()).first->parameters()[2] - parameters[2];
-
+ (*uncombinedState->begin()).first->parameters()[2] - parameters[2];
if (deltaPhi > M_PI) {
parameters[2] += 2 * M_PI;
} else if (deltaPhi < -M_PI) {
@@ -249,17 +250,12 @@ Trk::MultiComponentStateCombiner::combineWithWeight(
finalParameters, finalWeight, secondParameters, secondWeight);
const AmgSymMatrix(5)* firstMeasuredCov = firstTrackParameters->covariance();
- const AmgSymMatrix(5)* secondMeasuredCov =
- secondTrackParameters->covariance();
+ const AmgSymMatrix(5)* secondMeasuredCov = secondTrackParameters->covariance();
// Check to see if first track parameters are measured or not
if (firstMeasuredCov && secondMeasuredCov) {
AmgSymMatrix(5) finalMeasuredCov(*firstMeasuredCov);
- combineCovWithWeight(firstParameters,
- finalMeasuredCov,
- firstWeight,
- secondParameters,
- *secondMeasuredCov,
- secondWeight);
+ combineCovWithWeight(firstParameters, finalMeasuredCov, firstWeight,
+ secondParameters, *secondMeasuredCov, secondWeight);
mergeTo.first->updateParameters(finalParameters, finalMeasuredCov);
mergeTo.second = finalWeight;
} else {
@@ -267,7 +263,20 @@ Trk::MultiComponentStateCombiner::combineWithWeight(
mergeTo.second = finalWeight;
}
}
+/**
+ * Moment-preserving merge of two 5D components
+ * for example see
+ * Runnalls, Andrew R.(2007)
+ * Kullback-Leibler approach to Gaussian mixture reduction
+ * equations (2),(3),(4)
+ */
+// The following does heave use of Eigen
+// for covariance. Avoid out-of-line calls
+// to Eigen
+#if defined(__GNUC__)
+[[gnu::flatten]]
+#endif
void
Trk::MultiComponentStateCombiner::combineParametersWithWeight(
AmgVector(5) & firstParameters,
@@ -275,10 +284,7 @@ Trk::MultiComponentStateCombiner::combineParametersWithWeight(
const AmgVector(5) & secondParameters,
const double secondWeight)
{
-
double totalWeight = firstWeight + secondWeight;
- // Ensure that we don't have any problems with the cyclical nature of phi
- // Use first state as reference poin
double deltaPhi = firstParameters[2] - secondParameters[2];
if (deltaPhi > M_PI) {
firstParameters[2] -= 2 * M_PI;
@@ -286,8 +292,8 @@ Trk::MultiComponentStateCombiner::combineParametersWithWeight(
firstParameters[2] += 2 * M_PI;
}
firstParameters =
- firstWeight * firstParameters + secondWeight * secondParameters;
- firstParameters /= totalWeight;
+ (firstWeight * firstParameters + secondWeight * secondParameters) /
+ totalWeight;
// Ensure that phi is between -pi and pi
firstParameters[2] = CxxUtils::wrapToPi(firstParameters[2]);
firstWeight = totalWeight;
@@ -312,9 +318,9 @@ Trk::MultiComponentStateCombiner::combineCovWithWeight(
AmgVector(5) parameterDifference = firstParameters - secondParameters;
parameterDifference[2] = CxxUtils::wrapToPi(parameterDifference[2]);
parameterDifference /= totalWeight;
- firstMeasuredCov *= firstWeight;
- firstMeasuredCov += secondWeight * secondMeasuredCov;
- firstMeasuredCov /= totalWeight;
+ firstMeasuredCov =
+ (firstWeight * firstMeasuredCov + secondWeight * secondMeasuredCov) /
+ totalWeight;
firstMeasuredCov += firstWeight * secondWeight * parameterDifference *
parameterDifference.transpose();
}
@@ -410,4 +416,3 @@ Trk::MultiComponentStateCombiner::combine(
return mergedState;
}
-
--
GitLab