GCC Code Coverage Report


Directory: ../../../builds/dumux-repositories/
File: /builds/dumux-repositories/dumux/dumux/multidomain/embedded/cylinderintegration.hh
Date: 2024-09-21 20:52:54
Exec Total Coverage
Lines: 143 164 87.2%
Functions: 8 15 53.3%
Branches: 91 182 50.0%

Line Branch Exec Source
1 // -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 // vi: set et ts=4 sw=4 sts=4:
3 //
4 // SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
5 // SPDX-License-Identifier: GPL-3.0-or-later
6 //
7 /*!
8 * \file
9 * \ingroup EmbeddedCoupling
10 * \brief Integration over cylindrical and elliptic cylindrical domains
11 * Lowest order integration formulas that are mostly useful to evenly distribute
12 * mass in a cylindrical domain.
13 */
14
15 #ifndef DUMUX_MULTIDOMAIN_EMBEDDED_CYLINDERINTEGRATOR_HH
16 #define DUMUX_MULTIDOMAIN_EMBEDDED_CYLINDERINTEGRATOR_HH
17
18 #include <cmath>
19 #include <algorithm>
20 #include <numeric>
21 #include <iterator>
22 #include <utility>
23 #include <tuple>
24 #include <limits>
25
26 #include <dune/common/fvector.hh>
27
28 #include <dumux/common/math.hh>
29 #include <dumux/multidomain/embedded/circlepoints.hh>
30
31 namespace Dumux::EmbeddedCoupling {
32
33 /*!
34 * \ingroup EmbeddedCoupling
35 * \brief Helper class to integrate over a cylinder domain
36 * \note This is mostly useful if the integral is known and the
37 * integral mass has to be locally distributed to some non-matching domain
38 * \note The algorithm creates (almost) evenly spaced area elements on a circle
39 * and extrudes this pattern into a cylinder. Each sub-cell is an integration
40 * point with constant ansatz on the sub-cell (lowest order integration formula).
41 * Hence to improve the quality of the integral, increase the sample size.
42 * \note The volume integral of a constant function is exact
43 * See Beckers & Beckers (2012) doi:10.1016/j.comgeo.2012.01.011 for circle distribution
44 * and T. Koch PhD thesis (2020), Section 7.2.4.
45 */
46 template<class Scalar>
47 class CylinderIntegration
48 {
49 using GlobalPosition = Dune::FieldVector<Scalar, 3>;
50
51 public:
52 /*!
53 * \brief Constructor
54 * \param rStep characteristic relative integration length (positive real number between 0 and 1)
55 * \note half the characteristic length means 2*2*2=8 times more integration points
56 */
57 1 CylinderIntegration(const Scalar rStep)
58 4 {
59 1 rSamples_ = characteristicLengthToNumSamples_(rStep);
60
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1 initialize_();
61 1 }
62
63 /*!
64 * \brief Constructor
65 * \param rStep characteristic relative integration length in r-direction (positive real number between 0 and 1)
66 * \param zStep characteristic relative integration length in z-direction (positive real number between 0 and 1)
67 * \note Use this constructor to achieve a non-balanced (away from 1) aspect ratio between r and z-direction
68 */
69 6 CylinderIntegration(const Scalar rStep, const Scalar zStep)
70
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24 : zStepFixed_(true)
71 {
72 using std::ceil; using std::clamp;
73 6 rSamples_ = characteristicLengthToNumSamples_(rStep);
74 6 zSamples_ = characteristicLengthToNumSamples_(zStep);
75
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6 initialize_();
76 6 }
77
78 /*!
79 * \brief Set the geometry of the cylinder
80 * \param bottomCenter bottom center position
81 * \param topCenter top center position
82 * \param radius cylinder radius
83 * \param verbosity the verbosity level (default: 0 -> no terminal output)
84 */
85 1425 void setGeometry(const GlobalPosition& bottomCenter,
86 const GlobalPosition& topCenter,
87 const Scalar radius,
88 int verbosity = 0)
89 {
90 1425 const auto zAxis = (topCenter-bottomCenter);
91 1425 const auto height = zAxis.two_norm();
92 1425 const auto zAxisUnitVector = zAxis/height;
93
94 // compute step size in r-direction
95 1425 const auto rStep = radius/Scalar(rSamples_);
96
97 // compute zSamples from r samples if not specified by the user
98 using std::ceil;
99
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1425 if (!zStepFixed_)
100
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2 zSamples_ = std::max<std::size_t>(1, ceil(height/rStep));
101 1425 const auto zStep = height/Scalar(zSamples_);
102
103 // compute offsets for index calculation
104
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1425 auto kOffset = numRingSamples_;
105
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5700 std::partial_sum(kOffset.begin(), kOffset.end(), kOffset.begin());
106
107 // compute total number of samples
108 1425 numPoints_ = zSamples_*circleSamples_;
109
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1425 if (verbosity > 0)
110
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2 std::cout << "CylinderIntegration -- number of integration points: " << numPoints_ << std::endl;
111
112 // resize integration points and integration elements
113
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1425 integrationElement_.resize(numPoints_);
114
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1425 points_.resize(numPoints_);
115
116 // reserve enough memory for the points on each ring
117
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4275 std::vector<GlobalPosition> ringPoints;
118
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2850 ringPoints.reserve(numRingSamples_.back());
119
120 // compute integration points and integration elements
121
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2887 for (std::size_t i = 0; i < zSamples_; ++i)
122 {
123 // for each cylinder slice i
124 1462 auto sliceCenter = bottomCenter;
125 1462 sliceCenter.axpy((Scalar(i)+0.5)*zStep, zAxisUnitVector);
126
127 // generate circle points for each ring j
128
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25012 for (std::size_t j = 0; j < rSamples_; ++j)
129 {
130 23550 const auto r = (Scalar(j)+0.5)*rStep;
131
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47100 circlePoints(ringPoints, sincos_[j], sliceCenter, zAxisUnitVector, r);
132
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23550 const auto ringOffest = j > 0 ? kOffset[j-1] : 0;
133 23550 const auto ringSamples = numRingSamples_[j];
134 // volume of each element in ring
135 // total ring volume is given by M_PI*rStep*rStep*zStep*((j+1)^2 - j^2)
136 23550 const auto integrationElement = M_PI*rStep*rStep*zStep*(1.0 + 2.0*Scalar(j))/ringSamples;
137
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3461234 for (std::size_t k = 0; k < ringSamples; ++k)
138 {
139 3437684 const std::size_t idx = k + ringOffest + circleSamples_*i;
140 6875368 points_[idx] = ringPoints[k];
141 6875368 integrationElement_[idx] = integrationElement;
142 }
143 }
144 }
145 1425 }
146
147 //! The integration element of the ith integration point
148 Scalar integrationElement(std::size_t i) const
149
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24799942 { return integrationElement_[i]; }
150
151 //! The ith integration point
152 const GlobalPosition& integrationPoint(std::size_t i) const
153 24753418 { return points_[i]; }
154
155 //! The number of integration points
156 std::size_t size() const
157 { return numPoints_; }
158
159 private:
160 7 void initialize_()
161 {
162 // precompute number of cells in ring and total circle samples
163 7 circleSamples_ = 0;
164 7 numRingSamples_.resize(rSamples_);
165
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537 for (int j = 0; j < rSamples_; ++j)
166 {
167 // number of cells in ring j
168 using std::floor;
169 530 numRingSamples_[j] = floor(2*M_PI*(Scalar(j)+0.5));
170 530 circleSamples_ += numRingSamples_[j];
171 }
172
173 // optimization because calling too many sin/cos can be really expensive
174 7 sincos_.resize(rSamples_);
175
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537 for (int j = 0; j < rSamples_; ++j)
176 {
177 530 const auto numPoints = numRingSamples_[j];
178 530 sincos_[j].resize(2*numPoints);
179 530 Scalar t = 0 + 0.1;
180
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158910 for (std::size_t i = 0; i < numPoints; ++i)
181 {
182 using std::sin; using std::cos;
183
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316760 sincos_[j][2*i] = sin(t);
184
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158380 sincos_[j][2*i + 1] = cos(t);
185 158380 t += 2*M_PI/numPoints;
186
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158380 if (t > 2*M_PI) t -= 2*M_PI;
187 }
188 }
189 7 }
190
191 // invert characteristic length (between 0 and 1)
192 // and make sure there is no integer wrap around for small ratios
193 std::size_t characteristicLengthToNumSamples_(const Scalar cl) const
194 {
195 using std::clamp; using std::min; using std::max; using std::ceil; using std::nexttoward;
196 const Scalar clampedCl = clamp(cl, std::numeric_limits<Scalar>::min(), 1.0);
197 const Scalar floatNumSamples = ceil(1.0/clampedCl);
198 const Scalar largestValidFloat = nexttoward(std::numeric_limits<std::size_t>::max(), 0.0);
199 return static_cast<std::size_t>(min(floatNumSamples, largestValidFloat));
200 }
201
202 bool zStepFixed_ = false;
203 std::size_t zSamples_, rSamples_, numPoints_, circleSamples_;
204 std::vector<Scalar> integrationElement_;
205 std::vector<GlobalPosition> points_;
206 std::vector<std::size_t> numRingSamples_;
207 std::vector<std::vector<Scalar>> sincos_;
208 };
209
210 namespace Detail {
211 //! check if a point is in an ellipse
212 template<class GlobalPosition>
213 10880 inline bool pointInEllipse(const GlobalPosition& p,
214 const GlobalPosition& center,
215 const GlobalPosition& firstAxis,
216 const GlobalPosition& secondAxis,
217 const GlobalPosition& normal,
218 const typename GlobalPosition::value_type a,
219 const typename GlobalPosition::value_type b)
220 {
221 10880 const auto d = p-center;
222 // early return if point is not on the ellipse plane
223
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10880 if (d*normal > 1e-7*a)
224 return false;
225
226 // check if it's actually within the ellipse
227 const auto da = (d*firstAxis);
228 10880 const auto db = (d*secondAxis);
229
230 10880 return (da*da/(a*a) + db*db/(b*b) < 1.0);
231 }
232
233 //! construct evenly distributed integration points on an ellipse
234 template<class GlobalPosition>
235 inline std::pair<std::vector<GlobalPosition>, typename GlobalPosition::value_type>
236 6 ellipseIntegrationPoints(const GlobalPosition& center,
237 const GlobalPosition& firstUnitAxis,
238 const GlobalPosition& secondUnitAxis,
239 typename GlobalPosition::value_type a,
240 typename GlobalPosition::value_type b,
241 const GlobalPosition& normal,
242 typename GlobalPosition::value_type characteristicLength)
243 {
244 // choose step size in a-direction
245 6 const auto aStep = characteristicLength;
246
247 using std::floor;
248
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6 const std::size_t aSamples = std::max<std::size_t>(floor(2*a/aStep), 1);
249
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6 const std::size_t bSamples = std::max<std::size_t>(floor(2*b/aStep), 1);
250 6 const auto bStep = 2*b / bSamples;
251
252 // reserve upper limit estimate for memory needed
253
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6 std::vector<GlobalPosition> points;
254
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6 points.reserve(aSamples*bSamples);
255
256 // walk over lattice grid and reject points outside the ellipse
257 6 auto startAB = center;
258 6 startAB.axpy(-a + 0.5*aStep, firstUnitAxis);
259 6 startAB.axpy(-b + 0.5*bStep, secondUnitAxis);
260
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406 for (std::size_t as = 0; as < aSamples; ++as)
261 {
262 400 auto posA = startAB;
263 400 posA.axpy(as*aStep, firstUnitAxis);
264
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11280 for (std::size_t bs = 0; bs < bSamples; ++bs)
265 {
266 10880 auto pos = posA;
267 10880 pos.axpy(bs*bStep, secondUnitAxis);
268
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10880 if (pointInEllipse(pos, center, firstUnitAxis, secondUnitAxis, normal, a, b))
269
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8568 points.emplace_back(std::move(pos));
270 }
271 }
272 // return points and integration element
273
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12 return {points, aStep*bStep};
274 }
275 } // end namespace Detail
276
277 /*!
278 * \ingroup EmbeddedCoupling
279 * \brief Helper class to integrate over an elliptic cylinder domain
280 * \note The cylinder caps do not have to be orthogonal to the centerline axis but top and bottom cap are parallel planes
281 * \note This is mostly useful if the integral is known and the
282 * integral mass has to be locally distributed to some non-matching domain
283 * \note The algorithm is based on evenly spaced area elements with rejection sampling.
284 * To improve the quality of the integral, increase the sample size.
285 * \note The volume integral of a constant function is exact
286 * See Koch et al. (2020) https://doi.org/10.1016/j.jcp.2020.109369
287 */
288 template<class Scalar>
289
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6 class EllipticCylinderIntegration
290 {
291 using GlobalPosition = Dune::FieldVector<Scalar, 3>;
292
293 public:
294 /*!
295 * \brief Constructor
296 * \param relCharLength characteristic relative integration length (real number between 0 and 1)
297 * \note half the characteristic length means 2*2*2=8 times more integration points
298 */
299 3 explicit EllipticCylinderIntegration(const Scalar relCharLength)
300
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6 : relCharLength_(relCharLength)
301 {}
302
303 /*!
304 * \brief Set the geometry of elliptic cylinder
305 * \param bottomCenter bottom center position
306 * \param topCenter top center position
307 * \param firstAxis first ellipse axis (length corresponding to axis length)
308 * \param secondAxis second ellipse axis (length corresponding to axis length)
309 * \param verbosity the verbosity level (default: 0 -> no terminal output)
310 */
311 3 void setGeometry(const GlobalPosition& bottomCenter,
312 const GlobalPosition& topCenter,
313 const GlobalPosition& firstAxis,
314 const GlobalPosition& secondAxis,
315 int verbosity = 0)
316 {
317 3 const auto a = firstAxis.two_norm();
318 3 const auto b = secondAxis.two_norm();
319 3 const auto characteristicLength = relCharLength_*a;
320
321 3 auto firstUnitAxis = firstAxis; firstUnitAxis /= a;
322 3 auto secondUnitAxis = secondAxis; secondUnitAxis /= b;
323 3 const auto normal = crossProduct(firstUnitAxis, secondUnitAxis);
324
325 3 auto zAxis = (topCenter-bottomCenter);
326 3 const auto length = zAxis.two_norm();
327 3 zAxis /= length;
328 3 const auto height = (zAxis*normal)*length;
329 using std::floor;
330
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3 const std::size_t zSamples = std::max<std::size_t>(floor(height/characteristicLength), 1);
331 3 const auto zStep = length / Scalar(zSamples);
332 3 const auto zStepFactor = length/height;
333
334 // walk over lattice grid and reject points outside the ellipse
335 3 auto startZ = bottomCenter;
336 3 startZ.axpy(0.5*zStep, zAxis);
337
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6 auto [ellipseIPs, ellipseIntegrationElement]
338 = Detail::ellipseIntegrationPoints(startZ, firstUnitAxis, secondUnitAxis, a, b, normal, characteristicLength);
339
340 // compute total number of points
341
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3 const auto abPoints = ellipseIPs.size();
342 3 numPoints_ = abPoints*zSamples;
343
344 // first move in the first layer of ellipse integration points
345
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3 points_.clear();
346
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3 points_.reserve(numPoints_);
347 12 std::move(ellipseIPs.begin(), ellipseIPs.end(), std::back_inserter(points_));
348
349 // then extrude along the z axis
350 3 auto zStepVector = zAxis; zStepVector *= zStep;
351
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100 for (std::size_t zs = 1; zs < zSamples; ++zs)
352
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485 std::transform(points_.end() - abPoints, points_.end(), std::back_inserter(points_),
353 269640 [&](const auto& p){ return p + zStepVector; });
354
355 // computation and error correction for integral element to obtain exact integral of constant functions
356 3 integrationElement_ = ellipseIntegrationElement*zStep/zStepFactor;
357 3 const auto meanLocalError = (height*a*b*M_PI - integrationElement_*numPoints_)/Scalar(numPoints_);
358 3 integrationElement_ += meanLocalError;
359
360
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3 if (verbosity > 0)
361 {
362
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6 std::cout << "EllipticCylinderIntegration -- number of integration points: " << numPoints_ <<"\n";
363
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3 if (verbosity > 1)
364 std::cout << " -- a: " << a << ", b: " << b << ", h: " << height << "\n"
365 << " -- volume: " << integrationElement_*numPoints_ << " (expected " << height*a*b*M_PI << ")\n"
366 << " -- corrected a volume error of: " << meanLocalError/integrationElement_*100 << "%\n";
367 }
368 3 }
369
370 //! obtain ith integration element
371 Scalar integrationElement(std::size_t i) const
372 { return integrationElement_; }
373
374 //! obtain ith integration point
375 const GlobalPosition& integrationPoint(std::size_t i) const
376 278208 { return points_[i]; }
377
378 //! number of samples points
379 std::size_t size() const
380 { return numPoints_; }
381
382 private:
383 const Scalar relCharLength_;
384 std::size_t numPoints_;
385 Scalar integrationElement_;
386 std::vector<GlobalPosition> points_;
387 };
388
389 /*!
390 * \ingroup EmbeddedCoupling
391 * \brief Helper class to integrate over an elliptic domain
392 * \note This is mostly useful if the integral is known and the
393 * integral mass has to be locally distributed to some non-matching domain
394 * \note The algorithm is based on evenly spaced area elements with rejection sampling.
395 * To improve the quality of the integral, increase the sample size.
396 * \note The area integral of a constant function is exact
397 * See Koch et al. (2020) https://doi.org/10.1016/j.jcp.2020.109369
398 */
399 template<class Scalar>
400
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6 class EllipseIntegration
401 {
402 using GlobalPosition = Dune::FieldVector<Scalar, 3>;
403
404 public:
405 /*!
406 * \brief Constructor
407 * \param relCharLength characteristic relative integration length (real number between 0 and 1)
408 * \note half the characteristic length means 2*2=4 times more integration points
409 */
410 3 explicit EllipseIntegration(const Scalar relCharLength)
411
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6 : relCharLength_(relCharLength)
412 {}
413
414 /*!
415 * \brief set geometry of an ellipse
416 * \param center the center position
417 * \param firstAxis first ellipse axis (length corresponding to axis length)
418 * \param secondAxis second ellipse axis (length corresponding to axis length)
419 * \param verbosity the verbosity level (default: 0 -> no terminal output)
420 */
421 3 void setGeometry(const GlobalPosition& center,
422 const GlobalPosition& firstAxis,
423 const GlobalPosition& secondAxis,
424 int verbosity = 0)
425 {
426 3 const auto a = firstAxis.two_norm();
427 3 const auto b = secondAxis.two_norm();
428 3 const auto characteristicLength = relCharLength_*a;
429
430 3 auto firstUnitAxis = firstAxis; firstUnitAxis /= a;
431 3 auto secondUnitAxis = secondAxis; secondUnitAxis /= b;
432 3 const auto normal = crossProduct(firstUnitAxis, secondUnitAxis);
433
434 // generate integration points
435 3 std::tie(points_, integrationElement_)
436
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3 = Detail::ellipseIntegrationPoints(center, firstUnitAxis, secondUnitAxis, a, b, normal, characteristicLength);
437
438 // store number of sample points
439
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3 const auto abPoints = points_.size();
440 3 numPoints_ = abPoints;
441
442 // computation and error correction for integral element to obtain exact integral of constant functions
443 3 const auto meanLocalError = (a*b*M_PI - integrationElement_*numPoints_)/Scalar(numPoints_);
444 3 integrationElement_ += meanLocalError;
445
446
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3 if (verbosity > 0)
447 {
448 6 std::cout << "EllipseIntegration -- number of integration points: " << numPoints_ << "\n";
449
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3 if (verbosity > 1)
450 std::cout << " -- a: " << a << ", b: " << b << "\n"
451 << " -- area: " << integrationElement_*numPoints_ << " (expected " << a*b*M_PI << ")\n"
452 << " -- corrected an area error of: " << meanLocalError/integrationElement_*100 << "%\n";
453 }
454 3 }
455
456 //! obtain ith integration element
457 Scalar integrationElement(std::size_t i) const
458 { return integrationElement_; }
459
460 //! obtain ith integration point
461 const GlobalPosition& integrationPoint(std::size_t i) const
462 8568 { return points_[i]; }
463
464 //! number of integration points
465 std::size_t size() const
466 { return numPoints_; }
467
468 private:
469 const Scalar relCharLength_;
470 std::size_t numPoints_;
471 Scalar integrationElement_;
472 std::vector<GlobalPosition> points_;
473 };
474
475 } // end namespace Dumux::EmbeddedCoupling
476
477 #endif
478