invert z for correct definition

matthias-kleiner · Jan 3, 2024 · 8485d8f · 8485d8f
1 parent 62c2e49
commit 8485d8f
Showing 1 changed file with 9 additions and 6 deletions.
diff --git a/GPU/TPCFastTransformation/TPCFastTransform.h b/GPU/TPCFastTransformation/TPCFastTransform.h
@@ -264,21 +264,24 @@ class TPCFastTransform : public FlatObject
 
   GPUd() float getScaling(int slice, float z, const float* scale) const
   {
+    // invert to have 0 at central electrode and 250 at readout
+    z = GPUCommonMath::Abs(z - mCorrection.getMaxDriftLength(slice));
+
     const int idxValOffs = (slice < getGeometry().getNumberOfSlicesA()) ? 0 : NLUMIZBINS;
 
     float scaleVal = 0;
     // find closest z bins
-    const float absZ = GPUCommonMath::Abs(z);
+    // const float absZ = GPUCommonMath::Abs(z);
     const int offsZIdx = 2 * NLUMIZBINS;
     const float zMin = scale[offsZIdx];
     const float zMax = scale[offsZIdx + NLUMIZBINS - 1];
 
     int type = 0;
-    if (absZ < zMin) {
+    if (z < zMin) {
       type = 0;
       // if z value is smaller than min value return last valid value
       scaleVal = scale[idxValOffs];
-    } else if (absZ > zMax) {
+    } else if (z > zMax) {
       type = 1;
       // if z value is larger than max value return last valid value
       scaleVal = scale[idxValOffs + NLUMIZBINS - 1];
@@ -295,9 +298,9 @@ class TPCFastTransform : public FlatObject
         if (deltaZScaler < deltaZClosest) {
           deltaZClosest = deltaZScaler;
           idxZClosest = iz;
-          if (absZ == scale[idxZ]) {
+          if (z == scale[idxZ]) {
             idxZClosestN = iz;
-          } else if (absZ < scale[idxZ]) {
+          } else if (z < scale[idxZ]) {
             idxZClosestN = iz - 1;
           } else {
             idxZClosestN = iz + 1;
@@ -318,7 +321,7 @@ class TPCFastTransform : public FlatObject
         const float y1 = scale[idxValOffs + idx1];
         const float x0 = scale[offsZIdx + idx0];
         const float x1 = scale[offsZIdx + idx1];
-        const float x = absZ;
+        const float x = z;
         scaleVal = (y0 * (x1 - x) + y1 * (x - x0)) / (x1 - x0);
 
         GPUCA_DEBUG_STREAMER_CHECK(if (o2::utils::DebugStreamer::checkStream(o2::utils::StreamFlags::streamFastTransform)) {