From b526b9de4bb7c71e9f9d8d9e368addaff9bba522 Mon Sep 17 00:00:00 2001
From: Takashi Yamanaka <takashi.yamanaka@cern.ch>
Date: Thu, 16 Mar 2017 15:18:11 +0100
Subject: [PATCH] Merge branch 'update_atan2' into 'master'
Move to std::atan2, fix ATLASRECTS-3945
Closes ATLASRECTS-3945
See merge request !416
Former-commit-id: 86d170807d73cc3c2b001c77338254534ea0f218
---
.../MagFieldServices/src/AtlasFieldSvc.cxx | 65 +------------------
1 file changed, 2 insertions(+), 63 deletions(-)
diff --git a/MagneticField/MagFieldServices/src/AtlasFieldSvc.cxx b/MagneticField/MagFieldServices/src/AtlasFieldSvc.cxx
index ee1a1deaeea..3f3c615b326 100644
--- a/MagneticField/MagFieldServices/src/AtlasFieldSvc.cxx
+++ b/MagneticField/MagFieldServices/src/AtlasFieldSvc.cxx
@@ -31,10 +31,6 @@
#include "TFile.h"
#include "TTree.h"
-namespace {
- inline double atan2fast(double y, double x);
-}
-
/** Constructor **/
MagField::AtlasFieldSvc::AtlasFieldSvc(const std::string& name,ISvcLocator* svc) :
AthService(name,svc),
@@ -438,8 +434,8 @@ void MagField::AtlasFieldSvc::getField(const double *xyz, double *bxyz, double *
const double &x(xyz[0]);
const double &y(xyz[1]);
const double &z(xyz[2]);
- double r = sqrt(x * x + y * y);
- double phi = atan2fast(y, x);
+ double r = std::sqrt(x * x + y * y);
+ double phi = std::atan2(y, x);
// test if the cache is valid
if (!m_cache.inside(z, r, phi)) {
@@ -1420,60 +1416,3 @@ int MagField::AtlasFieldSvc::memSize() const
return size;
}
-//
-// Fast (less accurate) atan2()
-//
-namespace {
-
-double atan2fast(double y, double x)
-{
- const double halfpi(M_PI / 2.);
- const double sixthpi(M_PI / 6.);
- const double tansixthpi(tan(M_PI / 6.));
- const double tantwelfthpi(tan(M_PI / 12.));
-
- bool complement(false);
- bool sign(false);
- bool region(false);
-
- // test zeros
- if (y == 0.0) return 0.0;
- if (x == 0.0) return halfpi;
-
- // normalize range to -pi/12 to pi/12
- double z = y / x;
- if (z < 0) {
- z = -z;
- sign = true;
- }
- if (z > 1.0) {
- z = 1.0 / z;
- complement = true;
- }
- if (z > tantwelfthpi) {
- z = (z - tansixthpi) / (1 + tansixthpi * z);
- region = true;
- }
-
- // compute approximate atan
- const double c1 = 1.6867629106;
- const double c2 = 0.4378497304;
- const double c3 = 1.6867633134;
-
- double zz = z * z;
- double v = (z * (c1 + zz * c2) / (c3 + zz));
-
- // go back to the original range
- if (region) v += sixthpi;
- if (complement) v = halfpi - v;
- if (sign) v = -v;
- if (x < 0.0) {
- if (v < 0.0) v += M_PI;
- else v -= M_PI;
- }
-
- return v;
-}
-
-}
-
--
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