GPU: Use a unified constant instead of copy and paste for 0 field cut

Author: davidrohr

GPU/Common/GPUCommonConstants.h

@@ -20,6 +20,7 @@
 namespace o2::gpu::gpu_common_constants
 {
 static constexpr const float kCLight = 0.000299792458f; // TODO: Duplicate of MathConstants, fix this now that we use only OpenCL CPP
+static constexpr const float kZeroFieldCut = 0.013f;
 }
 
 #endif

GPU/GPUTracking/Merger/GPUTPCGMMerger.cxx

@@ -378,7 +378,7 @@ void GPUTPCGMMerger::SetMaxData(const GPUTrackingInOutPointers& io)
     }
   }
   mNMaxOutputTrackClusters = mRec->MemoryScalers()->NTPCMergedTrackHits(mNClusters);
-  if (CAMath::Abs(Param().polynomialField.GetNominalBz()) < (0.013f * gpu_common_constants::kCLight)) {
+  if (CAMath::Abs(Param().polynomialField.GetNominalBz()) < (gpu_common_constants::kZeroFieldCut * gpu_common_constants::kCLight)) {
     mNMaxTracks = mRec->MemoryScalers()->getValue(mNTotalSectorTracks, mNTotalSectorTracks); // 0 magnetic field
   } else {
     mNMaxTracks = mRec->MemoryScalers()->NTPCMergedTracks(mNTotalSectorTracks);
@@ -1743,7 +1743,7 @@ GPUd() void GPUTPCGMMerger::CollectMergedTracks(int32_t nBlocks, int32_t nThread
     p1.DzDs() = p2.DzDs();
     p1.QPt() = p2.QPt();
     mergedTrack.SetAlpha(p2.Alpha());
-    if (CAMath::Abs(Param().polynomialField.GetNominalBz()) < (0.013f * gpu_common_constants::kCLight)) {
+    if (CAMath::Abs(Param().polynomialField.GetNominalBz()) < (gpu_common_constants::kZeroFieldCut * gpu_common_constants::kCLight)) {
       p1.QPt() = 100.f / Param().rec.bz0Pt10MeV;
     }
 

GPU/GPUTracking/Merger/GPUTPCGMPolynomialFieldManager.cxx

@@ -195,7 +195,7 @@ int32_t GPUTPCGMPolynomialFieldManager::GetPolynomialField(float nominalFieldkG,
 
   StoredField_t type = kUnknown;
 
-  if (fabsf(nominalFieldkG) < 0.013f) {
+  if (fabsf(nominalFieldkG) < gpu_common_constants::kZeroFieldCut) {
     type = kUniform;
     nominalFieldkG = 0;
   } else if (fabsf(fabsf(nominalFieldkG) - 5.00668f) <= fabsf(fabsf(nominalFieldkG) - 2.f)) {