From 7cbb7c5993f5039d06d4563554a3666a5c519396 Mon Sep 17 00:00:00 2001
From: shahoian <ruben.shahoyan@cern.ch>
Date: Sat, 28 Feb 2026 17:54:43 +0100
Subject: [PATCH] Fix in the 3D field propagation final step

---
 .../Reconstruction/src/TrackParametrization.cxx      | 10 +++++-----
 .../src/TrackParametrizationWithError.cxx            | 12 ++++++------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/DataFormats/Reconstruction/src/TrackParametrization.cxx b/DataFormats/Reconstruction/src/TrackParametrization.cxx
index 7fe677a6e1c7a..4b850fe14086b 100644
--- a/DataFormats/Reconstruction/src/TrackParametrization.cxx
+++ b/DataFormats/Reconstruction/src/TrackParametrization.cxx
@@ -314,14 +314,14 @@ GPUd() bool TrackParametrization<value_T>::propagateParamTo(value_t xk, const di
 
   // Do the final correcting step to the target plane (linear approximation)
   value_t x = vecLab[0], y = vecLab[1], z = vecLab[2];
-  if (gpu::CAMath::Abs(dx) > constants::math::Almost0) {
+  if (gpu::CAMath::Abs(x - xk) > constants::math::Almost0) {
     if (gpu::CAMath::Abs(vecLab[3]) < constants::math::Almost0) {
       return false;
     }
-    dx = xk - vecLab[0];
-    x += dx;
-    y += vecLab[4] / vecLab[3] * dx;
-    z += vecLab[5] / vecLab[3] * dx;
+    auto dxFin = xk - vecLab[0];
+    x += dxFin;
+    y += vecLab[4] / vecLab[3] * dxFin;
+    z += vecLab[5] / vecLab[3] * dxFin;
   }
 
   // Calculate the track parameters
diff --git a/DataFormats/Reconstruction/src/TrackParametrizationWithError.cxx b/DataFormats/Reconstruction/src/TrackParametrizationWithError.cxx
index 2f8f15f783c60..93ff7e1a2eb82 100644
--- a/DataFormats/Reconstruction/src/TrackParametrizationWithError.cxx
+++ b/DataFormats/Reconstruction/src/TrackParametrizationWithError.cxx
@@ -776,14 +776,14 @@ GPUd() bool TrackParametrizationWithError<value_T>::propagateTo(value_t xk, cons
 
   // Do the final correcting step to the target plane (linear approximation)
   value_t x = vecLab[0], y = vecLab[1], z = vecLab[2];
-  if (gpu::CAMath::Abs(dx) > constants::math::Almost0) {
+  if (gpu::CAMath::Abs(x - xk) > constants::math::Almost0) {
     if (gpu::CAMath::Abs(vecLab[3]) < constants::math::Almost0) {
       return false;
     }
-    dx = xk - vecLab[0];
-    x += dx;
-    y += vecLab[4] / vecLab[3] * dx;
-    z += vecLab[5] / vecLab[3] * dx;
+    auto dxFin = xk - vecLab[0];
+    x += dxFin;
+    y += vecLab[4] / vecLab[3] * dxFin;
+    z += vecLab[5] / vecLab[3] * dxFin;
   }
 
   // Calculate the track parameters
@@ -896,7 +896,7 @@ GPUd() bool TrackParametrizationWithError<value_T>::propagateTo(value_t xk, Trac
 
   // Do the final correcting step to the target plane (linear approximation)
   value_t x = vecLab[0], y = vecLab[1], z = vecLab[2];
-  if (gpu::CAMath::Abs(dx) > constants::math::Almost0) {
+  if (gpu::CAMath::Abs(x - xk) > constants::math::Almost0) {
     if (gpu::CAMath::Abs(vecLab[3]) < constants::math::Almost0) {
       return false;
     }