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RealQuadraticEquation.hpp
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1 // This file is part of the Acts project.
2 //
3 // Copyright (C) 2017-2018 CERN for the benefit of the Acts project
4 //
5 // This Source Code Form is subject to the terms of the Mozilla Public
6 // License, v. 2.0. If a copy of the MPL was not distributed with this
7 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 
10 // RealQuadraticEquation.h, Acts project
12 
13 #pragma once
14 #include <cmath>
15 #include <utility>
16 
17 namespace Acts {
18 namespace detail {
19 
46 
48  double first;
49  double second;
50  int solutions;
51 
57  RealQuadraticEquation(double alpha, double beta, double gamma)
58  : first(0.), second(0.) {
59  double discriminant = beta * beta - 4 * alpha * gamma;
60  if (discriminant < 0) {
61  solutions = 0;
62  } else {
63  solutions = (discriminant == 0) ? 1 : 2;
64  double q = -0.5 * (beta + (beta > 0 ? std::sqrt(discriminant)
65  : -std::sqrt(discriminant)));
66  first = q / alpha;
67  second = gamma / q;
68  }
69  }
70 };
71 
72 } // namespace detail
73 } // namespace Acts