From 9444e1803e307671ac49e5e12f3682db36c015b5 Mon Sep 17 00:00:00 2001
From: Andres Rios Tascon <ariostas@gmail.com>
Date: Wed, 18 Dec 2024 13:46:37 -0800
Subject: [PATCH] Started removal of kVerticalModuleSlope

---
 RecoTracker/LSTCore/src/alpaka/MiniDoublet.h |  8 +++++---
 RecoTracker/LSTCore/src/alpaka/Quintuplet.h  | 10 ++++++----
 RecoTracker/LSTCore/src/alpaka/Segment.h     |  4 +++-
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/RecoTracker/LSTCore/src/alpaka/MiniDoublet.h b/RecoTracker/LSTCore/src/alpaka/MiniDoublet.h
index 80c7f6227e0cd..73dc7051fd93c 100644
--- a/RecoTracker/LSTCore/src/alpaka/MiniDoublet.h
+++ b/RecoTracker/LSTCore/src/alpaka/MiniDoublet.h
@@ -2,6 +2,7 @@
 #define RecoTracker_LSTCore_src_alpaka_MiniDoublet_h
 
 #include "HeterogeneousCore/AlpakaInterface/interface/workdivision.h"
+#include "FWCore/Utilities/interface/isFinite.h"
 
 #include "RecoTracker/LSTCore/interface/alpaka/Common.h"
 #include "RecoTracker/LSTCore/interface/MiniDoubletsSoA.h"
@@ -299,7 +300,8 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
     drprime = (moduleSeparation / alpaka::math::sin(acc, angleA + angleB)) * alpaka::math::sin(acc, angleA);
 
     // Compute arctan of the slope and take care of the slope = infinity case
-    absArctanSlope = ((slope != kVerticalModuleSlope) ? fabs(alpaka::math::atan(acc, slope)) : kPi / 2.f);
+    absArctanSlope =
+        ((slope != kVerticalModuleSlope && edm::isFinite(slope)) ? fabs(alpaka::math::atan(acc, slope)) : kPi / 2.f);
 
     // Depending on which quadrant the pixel hit lies, we define the angleM by shifting them slightly differently
     if (xp > 0 and yp > 0) {
@@ -322,8 +324,8 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
     ya = yp + drprime_y;
 
     // Compute the new strip hit position (if the slope value is in special condition take care of the exceptions)
-    if (slope ==
-        kVerticalModuleSlope)  // Designated for tilted module when the slope is infinity (module lying along y-axis)
+    if (slope == kVerticalModuleSlope ||
+        edm::isNotFinite(slope))  // Designated for tilted module when the slope is infinity (module lying along y-axis)
     {
       xn = xa;  // New x point is simply where the anchor is
       yn = yo;  // No shift in y
diff --git a/RecoTracker/LSTCore/src/alpaka/Quintuplet.h b/RecoTracker/LSTCore/src/alpaka/Quintuplet.h
index bcd9818a162d4..345a500848d78 100644
--- a/RecoTracker/LSTCore/src/alpaka/Quintuplet.h
+++ b/RecoTracker/LSTCore/src/alpaka/Quintuplet.h
@@ -657,8 +657,9 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
       // Computing sigmas is a very tricky affair
       // if the module is tilted or endcap, we need to use the slopes properly!
 
-      absArctanSlope = ((slopes[i] != kVerticalModuleSlope) ? alpaka::math::abs(acc, alpaka::math::atan(acc, slopes[i]))
-                                                            : kPi / 2.f);
+      absArctanSlope = ((slopes[i] != kVerticalModuleSlope && edm::isFinite(slopes[i]))
+                            ? alpaka::math::abs(acc, alpaka::math::atan(acc, slopes[i]))
+                            : kPi / 2.f);
 
       if (xs[i] > 0 and ys[i] > 0) {
         angleM = kPi / 2.f - absArctanSlope;
@@ -740,8 +741,9 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
     float chiSquared = 0.f;
     float absArctanSlope, angleM, xPrime, yPrime, sigma2;
     for (size_t i = 0; i < nPoints; i++) {
-      absArctanSlope = ((slopes[i] != kVerticalModuleSlope) ? alpaka::math::abs(acc, alpaka::math::atan(acc, slopes[i]))
-                                                            : kPi / 2.f);
+      absArctanSlope = ((slopes[i] != kVerticalModuleSlope && edm::isFinite(slopes[i]))
+                            ? alpaka::math::abs(acc, alpaka::math::atan(acc, slopes[i]))
+                            : kPi / 2.f);
       if (xs[i] > 0 and ys[i] > 0) {
         angleM = kPi / 2.f - absArctanSlope;
       } else if (xs[i] < 0 and ys[i] > 0) {
diff --git a/RecoTracker/LSTCore/src/alpaka/Segment.h b/RecoTracker/LSTCore/src/alpaka/Segment.h
index 8fba6d108c5e8..92ed042a77d65 100644
--- a/RecoTracker/LSTCore/src/alpaka/Segment.h
+++ b/RecoTracker/LSTCore/src/alpaka/Segment.h
@@ -1,6 +1,8 @@
 #ifndef RecoTracker_LSTCore_src_alpaka_Segment_h
 #define RecoTracker_LSTCore_src_alpaka_Segment_h
 
+#include <limits>
+
 #include "HeterogeneousCore/AlpakaInterface/interface/workdivision.h"
 
 #include "RecoTracker/LSTCore/interface/alpaka/Common.h"
@@ -246,7 +248,7 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
                                  mds.anchorY()[innerMDIndex] + circleRadius * alpaka::math::cos(acc, circlePhi)};
 
     //check which of the circles can accommodate r3LH better (we won't get perfect agreement)
-    float bestChiSquared = kVerticalModuleSlope;
+    float bestChiSquared = std::numeric_limits<float>::infinity();
     float chiSquared;
     size_t bestIndex;
     for (size_t i = 0; i < 2; i++) {