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InterpolatedBFieldMapTests.cpp
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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 
11 #include <boost/test/unit_test.hpp>
12 
13 #include "Acts/Definitions/Algebra.hpp"
14 #include "Acts/MagneticField/InterpolatedBFieldMap.hpp"
15 #include "Acts/MagneticField/MagneticFieldContext.hpp"
16 #include "Acts/MagneticField/MagneticFieldProvider.hpp"
17 #include "Acts/MagneticField/detail/SmallObjectCache.hpp"
18 #include "Acts/Tests/CommonHelpers/FloatComparisons.hpp"
19 #include "Acts/Utilities/Result.hpp"
20 #include "Acts/Utilities/VectorHelpers.hpp"
21 #include "Acts/Utilities/detail/Axis.hpp"
22 #include "Acts/Utilities/detail/AxisFwd.hpp"
23 #include "Acts/Utilities/detail/Grid.hpp"
24 #include "Acts/Utilities/detail/grid_helper.hpp"
25 
26 #include <array>
27 #include <cstddef>
28 #include <functional>
29 #include <optional>
30 #include <tuple>
31 #include <utility>
32 #include <vector>
33 
34 namespace tt = boost::test_tools;
35 
36 using Acts::VectorHelpers::perp;
37 
38 namespace Acts {
39 
40 namespace Test {
41 
42 // Create a test context
43 MagneticFieldContext mfContext = MagneticFieldContext();
44 
45 BOOST_AUTO_TEST_CASE(InterpolatedBFieldMap_rz) {
46  // definition of dummy BField
47  struct BField {
48  static Vector3 value(const std::array<double, 2>& rz) {
49  double r = rz.at(0);
50  double z = rz.at(1);
51  // linear in r and z so interpolation should be exact
52  return Vector3(r * z, 3 * r, -2 * z);
53  }
54  };
55 
56  // map (x,y,z) -> (r,z)
57  auto transformPos = [](const Vector3& pos) {
58  return Vector2(perp(pos), pos.z());
59  };
60 
61  // map (Bx,By,Bz) -> (Bx,By,Bz)
62  auto transformBField = [](const Vector3& field, const Vector3&) {
63  return field;
64  };
65 
66  // magnetic field known on grid in (r,z)
67  detail::EquidistantAxis r(0.0, 4.0, 4u);
68  detail::EquidistantAxis z(-5, 7, 6u);
69 
70  using Grid_t =
71  detail::Grid<Vector3, detail::EquidistantAxis, detail::EquidistantAxis>;
72  using BField_t = InterpolatedBFieldMap<Grid_t>;
73 
74  Grid_t g(std::make_tuple(std::move(r), std::move(z)));
75 
76  // set grid values
77  for (size_t i = 1; i <= g.numLocalBins().at(0) + 1; ++i) {
78  for (size_t j = 1; j <= g.numLocalBins().at(1) + 1; ++j) {
79  Grid_t::index_t indices = {{i, j}};
80  const auto& llCorner = g.lowerLeftBinEdge(indices);
81  g.atLocalBins(indices) = BField::value(llCorner);
82  }
83  }
84 
85  // create BField service
86  BField_t b{{transformPos, transformBField, std::move(g)}};
87 
88  auto bCacheAny = b.makeCache(mfContext);
89  BField_t::Cache& bCache = bCacheAny.get<BField_t::Cache>();
90 
91  auto check = [&](double i) {
92  BOOST_CHECK(b.isInside({0, 0, i * 4.9}));
93  BOOST_CHECK(!b.isInside({0, 0, i * 5.1}));
94 
95  BOOST_CHECK(b.isInside({i * 2.9, 0, 0}));
96  BOOST_CHECK(!b.isInside({i * 3.1, 0, 0}));
97 
98  BOOST_CHECK(b.isInside({0, i * 2.9, 0}));
99  BOOST_CHECK(!b.isInside({0, i * 3.1, 0}));
100 
101  BOOST_CHECK(b.isInside({2, 2.2, 0}));
102  BOOST_CHECK(!b.isInside({2, 3, 0}));
103 
104  BOOST_CHECK(b.isInside({i * 2, 2.2, 0}));
105  BOOST_CHECK(!b.isInside({i * 2, 3, 0}));
106 
107  BOOST_CHECK(b.isInside({2, i * 2.2, 0}));
108  BOOST_CHECK(!b.isInside({2, i * 3, 0}));
109 
110  BOOST_CHECK(b.isInside({i * 2, i * 2.2, 0}));
111  BOOST_CHECK(!b.isInside({i * 2, i * 3, 0}));
112  };
113 
114  check(1);
115  check(-1);
116 
117  Vector3 pos;
118  pos << -3, 2.5,
119  1.7; // this was previously checked, but is actually out of bounds
120  BOOST_CHECK(!b.isInside(pos));
121  BOOST_CHECK(!b.getField(pos, bCacheAny).ok());
122 
123  pos << -1.6, 2.5, 1.7;
124  BOOST_CHECK(b.isInside(pos));
125  CHECK_CLOSE_REL(b.getField(pos, bCacheAny).value(),
126  BField::value({{perp(pos), pos.z()}}), 1e-6);
127 
128  auto& c = *bCache.fieldCell;
129  BOOST_CHECK(c.isInside(transformPos(pos)));
130  CHECK_CLOSE_REL(c.getField(transformPos(pos)),
131  BField::value({{perp(pos), pos.z()}}), 1e-6);
132 
133  ActsMatrix<3, 3> deriv;
134 
135  pos << 1, 1, -5.5; // this position is outside the grid
136  BOOST_CHECK(!b.isInside(pos));
137  BOOST_CHECK(!b.getField(pos, bCacheAny).ok());
138  BOOST_CHECK(!b.getFieldGradient(pos, deriv, bCacheAny).ok());
139 
140  pos << 1, 6, -1.7; // this position is outside the grid
141  BOOST_CHECK(!b.isInside(pos));
142  BOOST_CHECK(!b.getField(pos, bCacheAny).ok());
143  BOOST_CHECK(!b.getFieldGradient(pos, deriv, bCacheAny).ok());
144 
145  pos << 0, 1.5, -2.5;
146  BOOST_CHECK(b.isInside(pos));
147  bCacheAny = b.makeCache(mfContext);
148  BField_t::Cache& bCache2 = bCacheAny.get<BField_t::Cache>();
149  CHECK_CLOSE_REL(b.getField(pos, bCacheAny).value(),
150  BField::value({{perp(pos), pos.z()}}), 1e-6);
151  c = *bCache2.fieldCell;
152  BOOST_CHECK(c.isInside(transformPos(pos)));
153  CHECK_CLOSE_REL(c.getField(transformPos(pos)),
154  BField::value({{perp(pos), pos.z()}}), 1e-6);
155 
156  pos << 2, 3, -4;
157  BOOST_CHECK(!b.isInside(pos));
158 
159  pos << 2, 2.2, -4;
160  BOOST_CHECK(b.isInside(pos));
161  bCacheAny = b.makeCache(mfContext);
162  BField_t::Cache& bCache3 = bCacheAny.get<BField_t::Cache>();
163  CHECK_CLOSE_REL(b.getField(pos, bCacheAny).value(),
164  BField::value({{perp(pos), pos.z()}}), 1e-6);
165  c = *bCache3.fieldCell;
166  BOOST_CHECK(c.isInside(transformPos(pos)));
167  CHECK_CLOSE_REL(c.getField(transformPos(pos)),
168  BField::value({{perp(pos), pos.z()}}), 1e-6);
169 
170  // some field cell tests
171  BOOST_CHECK(not c.isInside(transformPos((pos << 3, 2, -3.7).finished())));
172  BOOST_CHECK(not c.isInside(transformPos((pos << -2, 3, -4.7).finished())));
173  BOOST_CHECK(not c.isInside(transformPos((pos << -2, 3, 4.7).finished())));
174  BOOST_CHECK(c.isInside(transformPos((pos << 0, 2, -4.7).finished())));
175  BOOST_CHECK(not c.isInside(transformPos((pos << 5, 2, 14.).finished())));
176 }
177 } // namespace Test
178 
179 } // namespace Acts