18537555145

Committed 15 Oct 2025 05:37PM UTC coverage: 81.983% (-3.2%) from 85.194%

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Merge 3615a1fcc into e9077b137

Pull Request Pull Request #3417: Addition of a collision tracking feature

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82.61

/src/distribution.cpp

#include "openmc/distribution.h"

#include <algorithm> // for copy
#include <array>
#include <cmath>     // for sqrt, floor, max
#include <iterator>  // for back_inserter
#include <numeric>   // for accumulate
#include <stdexcept> // for runtime_error
#include <string>    // for string, stod

#include "openmc/error.h"
#include "openmc/math_functions.h"
#include "openmc/random_dist.h"
#include "openmc/random_lcg.h"
#include "openmc/xml_interface.h"

namespace openmc {

//==============================================================================
// DiscreteIndex implementation
//==============================================================================

DiscreteIndex::DiscreteIndex(pugi::xml_node node)
{
  auto params = get_node_array<double>(node, "parameters");
  std::size_t n = params.size() / 2;

  assign({params.data() + n, n});
}

DiscreteIndex::DiscreteIndex(span<const double> p)
{
  assign(p);
}

void DiscreteIndex::assign(span<const double> p)
{
  prob_.assign(p.begin(), p.end());

  this->init_alias();
}

void DiscreteIndex::init_alias()
{
  normalize();

  // The initialization and sampling method is based on Vose
  // (DOI: 10.1109/32.92917)
  // Vectors for large and small probabilities based on 1/n
  vector<size_t> large;
  vector<size_t> small;

  size_t n = prob_.size();

  // Set and allocate memory
  alias_.assign(n, 0);

  // Fill large and small vectors based on 1/n
  for (size_t i = 0; i < n; i++) {
    prob_[i] *= n;
    if (prob_[i] > 1.0) {
      large.push_back(i);
    } else {
      small.push_back(i);
    }
  }

  while (!large.empty() && !small.empty()) {
    int j = small.back();
    int k = large.back();

    // Remove last element of small
    small.pop_back();

    // Update probability and alias based on Vose's algorithm
    prob_[k] += prob_[j] - 1.0;
    alias_[j] = k;

    // Move large index to small vector, if it is no longer large
    if (prob_[k] < 1.0) {
      small.push_back(k);
      large.pop_back();
    }
  }
}

size_t DiscreteIndex::sample(uint64_t* seed) const
{
  // Alias sampling of discrete distribution
  size_t n = prob_.size();
  if (n > 1) {
    size_t u = prn(seed) * n;
    if (prn(seed) < prob_[u]) {
      return u;
    } else {
      return alias_[u];
    }
  } else {
    return 0;
  }
}

void DiscreteIndex::normalize()
{
  // Renormalize density function so that it sums to unity. Note that we save
  // the integral of the distribution so that if it is used as part of another
  // distribution (e.g., Mixture), we know its relative strength.
  integral_ = std::accumulate(prob_.begin(), prob_.end(), 0.0);
  for (auto& p_i : prob_) {
    p_i /= integral_;
  }
}

//==============================================================================
// Discrete implementation
//==============================================================================

Discrete::Discrete(pugi::xml_node node) : di_(node)
{
  auto params = get_node_array<double>(node, "parameters");

  std::size_t n = params.size() / 2;

  x_.assign(params.begin(), params.begin() + n);
}

Discrete::Discrete(const double* x, const double* p, size_t n) : di_({p, n})
{

  x_.assign(x, x + n);
}

double Discrete::sample(uint64_t* seed) const
{
  return x_[di_.sample(seed)];
}

//==============================================================================
// Uniform implementation
//==============================================================================

Uniform::Uniform(pugi::xml_node node)
{
  auto params = get_node_array<double>(node, "parameters");
  if (params.size() != 2) {
    fatal_error("Uniform distribution must have two "
                "parameters specified.");
  }

  a_ = params.at(0);
  b_ = params.at(1);
}

double Uniform::sample(uint64_t* seed) const
{
  return a_ + prn(seed) * (b_ - a_);
}

//==============================================================================
// PowerLaw implementation
//==============================================================================

PowerLaw::PowerLaw(pugi::xml_node node)
{
  auto params = get_node_array<double>(node, "parameters");
  if (params.size() != 3) {
    fatal_error("PowerLaw distribution must have three "
                "parameters specified.");
  }

  const double a = params.at(0);
  const double b = params.at(1);
  const double n = params.at(2);

  offset_ = std::pow(a, n + 1);
  span_ = std::pow(b, n + 1) - offset_;
  ninv_ = 1 / (n + 1);
}

double PowerLaw::sample(uint64_t* seed) const
{
  return std::pow(offset_ + prn(seed) * span_, ninv_);
}

//==============================================================================
// Maxwell implementation
//==============================================================================

Maxwell::Maxwell(pugi::xml_node node)
{
  theta_ = std::stod(get_node_value(node, "parameters"));
}

double Maxwell::sample(uint64_t* seed) const
{
  return maxwell_spectrum(theta_, seed);
}

//==============================================================================
// Watt implementation
//==============================================================================

Watt::Watt(pugi::xml_node node)
{
  auto params = get_node_array<double>(node, "parameters");
  if (params.size() != 2)
    openmc::fatal_error("Watt energy distribution must have two "
                        "parameters specified.");

  a_ = params.at(0);
  b_ = params.at(1);
}

double Watt::sample(uint64_t* seed) const
{
  return watt_spectrum(a_, b_, seed);
}

//==============================================================================
// Normal implementation
//==============================================================================
Normal::Normal(pugi::xml_node node)
{
  auto params = get_node_array<double>(node, "parameters");
  if (params.size() != 2) {
    openmc::fatal_error("Normal energy distribution must have two "
                        "parameters specified.");
  }

  mean_value_ = params.at(0);
  std_dev_ = params.at(1);
}

double Normal::sample(uint64_t* seed) const
{
  return normal_variate(mean_value_, std_dev_, seed);
}

//==============================================================================
// Tabular implementation
//==============================================================================

Tabular::Tabular(pugi::xml_node node)
{
  if (check_for_node(node, "interpolation")) {
    std::string temp = get_node_value(node, "interpolation");
    if (temp == "histogram") {
      interp_ = Interpolation::histogram;
    } else if (temp == "linear-linear") {
      interp_ = Interpolation::lin_lin;
    } else {
      openmc::fatal_error(
        "Unsupported interpolation type for distribution: " + temp);
    }
  } else {
    interp_ = Interpolation::histogram;
  }

  // Read and initialize tabular distribution. If number of parameters is odd,
  // add an extra zero for the 'p' array.
  auto params = get_node_array<double>(node, "parameters");
  if (params.size() % 2 != 0) {
    params.push_back(0.0);
  }
  std::size_t n = params.size() / 2;
  const double* x = params.data();
  const double* p = x + n;
  init(x, p, n);
}

Tabular::Tabular(const double* x, const double* p, int n, Interpolation interp,
  const double* c)
  : interp_ {interp}
{
  init(x, p, n, c);
}

void Tabular::init(
  const double* x, const double* p, std::size_t n, const double* c)
{
  // Copy x/p arrays into vectors
  std::copy(x, x + n, std::back_inserter(x_));
  std::copy(p, p + n, std::back_inserter(p_));

  // Check interpolation parameter
  if (interp_ != Interpolation::histogram &&
      interp_ != Interpolation::lin_lin) {
    openmc::fatal_error("Only histogram and linear-linear interpolation "
                        "for tabular distribution is supported.");
  }

  // Calculate cumulative distribution function
  if (c) {
    std::copy(c, c + n, std::back_inserter(c_));
  } else {
    c_.resize(n);
    c_[0] = 0.0;
    for (int i = 1; i < n; ++i) {
      if (interp_ == Interpolation::histogram) {
        c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]);
      } else if (interp_ == Interpolation::lin_lin) {
        c_[i] = c_[i - 1] + 0.5 * (p_[i - 1] + p_[i]) * (x_[i] - x_[i - 1]);
      }
    }
  }

  // Normalize density and distribution functions. Note that we save the
  // integral of the distribution so that if it is used as part of another
  // distribution (e.g., Mixture), we know its relative strength.
  integral_ = c_[n - 1];
  for (int i = 0; i < n; ++i) {
    p_[i] = p_[i] / integral_;
    c_[i] = c_[i] / integral_;
  }
}

double Tabular::sample(uint64_t* seed) const
{
  // Sample value of CDF
  double c = prn(seed);

  // Find first CDF bin which is above the sampled value
  double c_i = c_[0];
  int i;
  std::size_t n = c_.size();
  for (i = 0; i < n - 1; ++i) {
    if (c <= c_[i + 1])
      break;
    c_i = c_[i + 1];
  }

  // Determine bounding PDF values
  double x_i = x_[i];
  double p_i = p_[i];

  if (interp_ == Interpolation::histogram) {
    // Histogram interpolation
    if (p_i > 0.0) {
      return x_i + (c - c_i) / p_i;
    } else {
      return x_i;
    }
  } else {
    // Linear-linear interpolation
    double x_i1 = x_[i + 1];
    double p_i1 = p_[i + 1];

    double m = (p_i1 - p_i) / (x_i1 - x_i);
    if (m == 0.0) {
      return x_i + (c - c_i) / p_i;
    } else {
      return x_i +
             (std::sqrt(std::max(0.0, p_i * p_i + 2 * m * (c - c_i))) - p_i) /
               m;
    }
  }
}

//==============================================================================
// Equiprobable implementation
//==============================================================================

double Equiprobable::sample(uint64_t* seed) const
{
  std::size_t n = x_.size();

  double r = prn(seed);
  int i = std::floor((n - 1) * r);

  double xl = x_[i];
  double xr = x_[i + i];
  return xl + ((n - 1) * r - i) * (xr - xl);
}

//==============================================================================
// Mixture implementation
//==============================================================================

Mixture::Mixture(pugi::xml_node node)
{
  double cumsum = 0.0;
  for (pugi::xml_node pair : node.children("pair")) {
    // Check that required data exists
    if (!pair.attribute("probability"))
      fatal_error("Mixture pair element does not have probability.");
    if (!pair.child("dist"))
      fatal_error("Mixture pair element does not have a distribution.");

    // cummulative sum of probabilities
    double p = std::stod(pair.attribute("probability").value());

    // Save cummulative probability and distribution
    auto dist = distribution_from_xml(pair.child("dist"));
    cumsum += p * dist->integral();

    distribution_.push_back(std::make_pair(cumsum, std::move(dist)));
  }

  // Save integral of distribution
  integral_ = cumsum;

  // Normalize cummulative probabilities to 1
  for (auto& pair : distribution_) {
    pair.first /= cumsum;
  }
}

double Mixture::sample(uint64_t* seed) const
{
  // Sample value of CDF
  const double p = prn(seed);

  // find matching distribution
  const auto it = std::lower_bound(distribution_.cbegin(), distribution_.cend(),
    p, [](const DistPair& pair, double p) { return pair.first < p; });

  // This should not happen. Catch it
  assert(it != distribution_.cend());

  // Sample the chosen distribution
  return it->second->sample(seed);
}

//==============================================================================
// Helper function
//==============================================================================

UPtrDist distribution_from_xml(pugi::xml_node node)
{
  if (!check_for_node(node, "type"))
    openmc::fatal_error("Distribution type must be specified.");

  // Determine type of distribution
  std::string type = get_node_value(node, "type", true, true);

  // Allocate extension of Distribution
  UPtrDist dist;
  if (type == "uniform") {
    dist = UPtrDist {new Uniform(node)};
  } else if (type == "powerlaw") {
    dist = UPtrDist {new PowerLaw(node)};
  } else if (type == "maxwell") {
    dist = UPtrDist {new Maxwell(node)};
  } else if (type == "watt") {
    dist = UPtrDist {new Watt(node)};
  } else if (type == "normal") {
    dist = UPtrDist {new Normal(node)};
  } else if (type == "discrete") {
    dist = UPtrDist {new Discrete(node)};
  } else if (type == "tabular") {
    dist = UPtrDist {new Tabular(node)};
  } else if (type == "mixture") {
    dist = UPtrDist {new Mixture(node)};
  } else if (type == "muir") {
    openmc::fatal_error(
      "'muir' distributions are now specified using the openmc.stats.muir() "
      "function in Python. Please regenerate your XML files.");
  } else {
    openmc::fatal_error("Invalid distribution type: " + type);
  }
  return dist;
}

} // namespace openmc

1	#include "openmc/distribution.h"
2
3	#include <algorithm> // for copy
4	#include <array>
5	#include <cmath> // for sqrt, floor, max
6	#include <iterator> // for back_inserter
7	#include <numeric> // for accumulate
8	#include <stdexcept> // for runtime_error
9	#include <string> // for string, stod
10
11	#include "openmc/error.h"
12	#include "openmc/math_functions.h"
13	#include "openmc/random_dist.h"
14	#include "openmc/random_lcg.h"
15	#include "openmc/xml_interface.h"
16
17	namespace openmc {
18
19	//==============================================================================
20	// DiscreteIndex implementation
21	//==============================================================================
22
23	DiscreteIndex::DiscreteIndex(pugi::xml_node node)	25,864✔
24	{
25	auto params = get_node_array<double>(node, "parameters");	25,864✔
26	std::size_t n = params.size() / 2;	25,864✔
27
28	assign({params.data() + n, n});	25,864✔
29	}	25,864✔
30
31	DiscreteIndex::DiscreteIndex(span<const double> p)	46,940✔
32	{
33	assign(p);	46,940✔
34	}	46,940✔
35
36	void DiscreteIndex::assign(span<const double> p)	80,981✔
37	{
38	prob_.assign(p.begin(), p.end());	80,981✔
39
40	this->init_alias();	80,981✔
41	}	80,981✔
42
43	void DiscreteIndex::init_alias()	80,981✔
44	{
45	normalize();	80,981✔
46
47	// The initialization and sampling method is based on Vose
48	// (DOI: 10.1109/32.92917)
49	// Vectors for large and small probabilities based on 1/n
50	vector<size_t> large;	80,981✔
51	vector<size_t> small;	80,981✔
52
53	size_t n = prob_.size();	80,981✔
54
55	// Set and allocate memory
56	alias_.assign(n, 0);	80,981✔
57
58	// Fill large and small vectors based on 1/n
59	for (size_t i = 0; i < n; i++) {	1,544,811✔
60	prob_[i] *= n;	1,463,830✔
61	if (prob_[i] > 1.0) {	1,463,830✔
62	large.push_back(i);	218,761✔
63	} else {
64	small.push_back(i);	1,245,069✔
65	}
66	}
67
68	while (!large.empty() && !small.empty()) {	1,389,893✔
69	int j = small.back();	1,308,912✔
70	int k = large.back();	1,308,912✔
71
72	// Remove last element of small
73	small.pop_back();	1,308,912✔
74
75	// Update probability and alias based on Vose's algorithm
76	prob_[k] += prob_[j] - 1.0;	1,308,912✔
77	alias_[j] = k;	1,308,912✔
78
79	// Move large index to small vector, if it is no longer large
80	if (prob_[k] < 1.0) {	1,308,912✔
81	small.push_back(k);	211,005✔
82	large.pop_back();	211,005✔
83	}
84	}
85	}	80,981✔
86
87	size_t DiscreteIndex::sample(uint64_t* seed) const	64,412,619✔
88	{
89	// Alias sampling of discrete distribution
90	size_t n = prob_.size();	64,412,619✔
91	if (n > 1) {	64,412,619✔
92	size_t u = prn(seed) * n;	14,321,912✔
93	if (prn(seed) < prob_[u]) {	14,321,912✔
94	return u;	8,894,255✔
95	} else {
96	return alias_[u];	5,427,657✔
97	}
98	} else {
99	return 0;	50,090,707✔
100	}
101	}
102
103	void DiscreteIndex::normalize()	80,981✔
104	{
105	// Renormalize density function so that it sums to unity. Note that we save
106	// the integral of the distribution so that if it is used as part of another
107	// distribution (e.g., Mixture), we know its relative strength.
108	integral_ = std::accumulate(prob_.begin(), prob_.end(), 0.0);	80,981✔
109	for (auto& p_i : prob_) {	1,544,811✔
110	p_i /= integral_;	1,463,830✔
111	}
112	}	80,981✔
113
114	//==============================================================================
115	// Discrete implementation
116	//==============================================================================
117
118	Discrete::Discrete(pugi::xml_node node) : di_(node)	25,864✔
119	{
120	auto params = get_node_array<double>(node, "parameters");	25,864✔
121
122	std::size_t n = params.size() / 2;	25,864✔
123
124	x_.assign(params.begin(), params.begin() + n);	25,864✔
125	}	25,864✔
126
127	Discrete::Discrete(const double* x, const double* p, size_t n) : di_({p, n})	46,940✔
128	{
129
130	x_.assign(x, x + n);	46,940✔
131	}	46,940✔
132
133	double Discrete::sample(uint64_t* seed) const	61,255,441✔
134	{
135	return x_[di_.sample(seed)];	61,255,441✔
136	}
137
138	//==============================================================================
139	// Uniform implementation
140	//==============================================================================
141
142	Uniform::Uniform(pugi::xml_node node)	256✔
143	{
144	auto params = get_node_array<double>(node, "parameters");	256✔
145	if (params.size() != 2) {	256!
146	fatal_error("Uniform distribution must have two "	×
147	"parameters specified.");
148	}
149
150	a_ = params.at(0);	256✔
151	b_ = params.at(1);	256✔
152	}	256✔
153
154	double Uniform::sample(uint64_t* seed) const	285,116✔
155	{
156	return a_ + prn(seed) * (b_ - a_);	285,116✔
157	}
158
159	//==============================================================================
160	// PowerLaw implementation
161	//==============================================================================
162
163	PowerLaw::PowerLaw(pugi::xml_node node)	32✔
164	{
165	auto params = get_node_array<double>(node, "parameters");	32✔
166	if (params.size() != 3) {	32!
167	fatal_error("PowerLaw distribution must have three "	×
168	"parameters specified.");
169	}
170
171	const double a = params.at(0);	32✔
172	const double b = params.at(1);	32✔
173	const double n = params.at(2);	32✔
174
175	offset_ = std::pow(a, n + 1);	32✔
176	span_ = std::pow(b, n + 1) - offset_;	32✔
177	ninv_ = 1 / (n + 1);	32✔
178	}	32✔
179
180	double PowerLaw::sample(uint64_t* seed) const	2,222✔
181	{
182	return std::pow(offset_ + prn(seed) * span_, ninv_);	2,222✔
183	}
184
185	//==============================================================================
186	// Maxwell implementation
187	//==============================================================================
188
189	Maxwell::Maxwell(pugi::xml_node node)	64✔
190	{
191	theta_ = std::stod(get_node_value(node, "parameters"));	64✔
192	}	64✔
193
194	double Maxwell::sample(uint64_t* seed) const	3,883✔
195	{
196	return maxwell_spectrum(theta_, seed);	3,883✔
197	}
198
199	//==============================================================================
200	// Watt implementation
201	//==============================================================================
202
203	Watt::Watt(pugi::xml_node node)	96✔
204	{
205	auto params = get_node_array<double>(node, "parameters");	96✔
206	if (params.size() != 2)	96!
207	openmc::fatal_error("Watt energy distribution must have two "	×
208	"parameters specified.");
209
210	a_ = params.at(0);	96✔
211	b_ = params.at(1);	96✔
212	}	96✔
213
214	double Watt::sample(uint64_t* seed) const	11,421,433✔
215	{
216	return watt_spectrum(a_, b_, seed);	11,421,433✔
217	}
218
219	//==============================================================================
220	// Normal implementation
221	//==============================================================================
222	Normal::Normal(pugi::xml_node node)	×
223	{
224	auto params = get_node_array<double>(node, "parameters");	×
225	if (params.size() != 2) {	×
226	openmc::fatal_error("Normal energy distribution must have two "	×
227	"parameters specified.");
228	}
229
230	mean_value_ = params.at(0);	×
231	std_dev_ = params.at(1);	×
UNCOV 232	}	×
233
234	double Normal::sample(uint64_t* seed) const	×
235	{
236	return normal_variate(mean_value_, std_dev_, seed);	×
237	}
238
239	//==============================================================================
240	// Tabular implementation
241	//==============================================================================
242
243	Tabular::Tabular(pugi::xml_node node)	7,285✔
244	{
245	if (check_for_node(node, "interpolation")) {	7,285!
246	std::string temp = get_node_value(node, "interpolation");	7,285✔
247	if (temp == "histogram") {	7,285✔
248	interp_ = Interpolation::histogram;	7,221✔
249	} else if (temp == "linear-linear") {	64!
250	interp_ = Interpolation::lin_lin;	64✔
251	} else {
252	openmc::fatal_error(	×
253	"Unsupported interpolation type for distribution: " + temp);	×
254	}
255	} else {	7,285✔
256	interp_ = Interpolation::histogram;	×
257	}
258
259	// Read and initialize tabular distribution. If number of parameters is odd,
260	// add an extra zero for the 'p' array.
261	auto params = get_node_array<double>(node, "parameters");	7,285✔
262	if (params.size() % 2 != 0) {	7,285!
263	params.push_back(0.0);	×
264	}
265	std::size_t n = params.size() / 2;	7,285✔
266	const double* x = params.data();	7,285✔
267	const double* p = x + n;	7,285✔
268	init(x, p, n);	7,285✔
269	}	7,285✔
270
271	Tabular::Tabular(const double* x, const double* p, int n, Interpolation interp,	50,802,628✔
272	const double* c)	50,802,628✔
273	: interp_ {interp}	50,802,628✔
274	{
275	init(x, p, n, c);	50,802,628✔
276	}	50,802,628✔
277
278	void Tabular::init(	50,809,913✔
279	const double* x, const double* p, std::size_t n, const double* c)
280	{
281	// Copy x/p arrays into vectors
282	std::copy(x, x + n, std::back_inserter(x_));	50,809,913✔
283	std::copy(p, p + n, std::back_inserter(p_));	50,809,913✔
284
285	// Check interpolation parameter
286	if (interp_ != Interpolation::histogram &&	50,809,913✔
287	interp_ != Interpolation::lin_lin) {	42,708,810!
288	openmc::fatal_error("Only histogram and linear-linear interpolation "	×
289	"for tabular distribution is supported.");
290	}
291
292	// Calculate cumulative distribution function
293	if (c) {	50,809,913✔
294	std::copy(c, c + n, std::back_inserter(c_));	50,802,628✔
295	} else {
296	c_.resize(n);	7,285✔
297	c_[0] = 0.0;	7,285✔
298	for (int i = 1; i < n; ++i) {	90,492✔
299	if (interp_ == Interpolation::histogram) {	83,207✔
300	c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]);	83,079✔
301	} else if (interp_ == Interpolation::lin_lin) {	128!
302	c_[i] = c_[i - 1] + 0.5 * (p_[i - 1] + p_[i]) * (x_[i] - x_[i - 1]);	128✔
303	}
304	}
305	}
306
307	// Normalize density and distribution functions. Note that we save the
308	// integral of the distribution so that if it is used as part of another
309	// distribution (e.g., Mixture), we know its relative strength.
310	integral_ = c_[n - 1];	50,809,913✔
311	for (int i = 0; i < n; ++i) {	736,828,554✔
312	p_[i] = p_[i] / integral_;	686,018,641✔
313	c_[i] = c_[i] / integral_;	686,018,641✔
314	}
315	}	50,809,913✔
316
317	double Tabular::sample(uint64_t* seed) const	612,207,433✔
318	{
319	// Sample value of CDF
320	double c = prn(seed);	612,207,433✔
321
322	// Find first CDF bin which is above the sampled value
323	double c_i = c_[0];	612,207,433✔
324	int i;
325	std::size_t n = c_.size();	612,207,433✔
326	for (i = 0; i < n - 1; ++i) {	2,147,483,647!
327	if (c <= c_[i + 1])	2,147,483,647✔
328	break;	612,207,433✔
329	c_i = c_[i + 1];	1,625,724,873✔
330	}
331
332	// Determine bounding PDF values
333	double x_i = x_[i];	612,207,433✔
334	double p_i = p_[i];	612,207,433✔
335
336	if (interp_ == Interpolation::histogram) {	612,207,433✔
337	// Histogram interpolation
338	if (p_i > 0.0) {	3,421,748!
339	return x_i + (c - c_i) / p_i;	3,421,748✔
340	} else {
341	return x_i;	×
342	}
343	} else {
344	// Linear-linear interpolation
345	double x_i1 = x_[i + 1];	608,785,685✔
346	double p_i1 = p_[i + 1];	608,785,685✔
347
348	double m = (p_i1 - p_i) / (x_i1 - x_i);	608,785,685✔
349	if (m == 0.0) {	608,785,685✔
350	return x_i + (c - c_i) / p_i;	316,491,886✔
351	} else {
352	return x_i +
353	(std::sqrt(std::max(0.0, p_i * p_i + 2 * m * (c - c_i))) - p_i) /	292,293,799✔
354	m;	292,293,799✔
355	}
356	}
357	}
358
359	//==============================================================================
360	// Equiprobable implementation
361	//==============================================================================
362
363	double Equiprobable::sample(uint64_t* seed) const	×
364	{
365	std::size_t n = x_.size();	×
366
367	double r = prn(seed);	×
368	int i = std::floor((n - 1) * r);	×
369
370	double xl = x_[i];	×
371	double xr = x_[i + i];	×
372	return xl + ((n - 1) * r - i) * (xr - xl);	×
373	}
374
375	//==============================================================================
376	// Mixture implementation
377	//==============================================================================
378
379	Mixture::Mixture(pugi::xml_node node)	48✔
380	{
381	double cumsum = 0.0;	48✔
382	for (pugi::xml_node pair : node.children("pair")) {	192✔
383	// Check that required data exists
384	if (!pair.attribute("probability"))	144!
385	fatal_error("Mixture pair element does not have probability.");	×
386	if (!pair.child("dist"))	144!
387	fatal_error("Mixture pair element does not have a distribution.");	×
388
389	// cummulative sum of probabilities
390	double p = std::stod(pair.attribute("probability").value());	144✔
391
392	// Save cummulative probability and distribution
393	auto dist = distribution_from_xml(pair.child("dist"));	144✔
394	cumsum += p * dist->integral();	144✔
395
396	distribution_.push_back(std::make_pair(cumsum, std::move(dist)));	144✔
397	}	144✔
398
399	// Save integral of distribution
400	integral_ = cumsum;	48✔
401
402	// Normalize cummulative probabilities to 1
403	for (auto& pair : distribution_) {	192✔
404	pair.first /= cumsum;	144✔
405	}
406	}	48✔
407
408	double Mixture::sample(uint64_t* seed) const	3,564✔
409	{
410	// Sample value of CDF
411	const double p = prn(seed);	3,564✔
412
413	// find matching distribution
414	const auto it = std::lower_bound(distribution_.cbegin(), distribution_.cend(),	3,564✔
415	p, [](const DistPair& pair, double p) { return pair.first < p; });	7,128✔
416
417	// This should not happen. Catch it
418	assert(it != distribution_.cend());	2,916!
419
420	// Sample the chosen distribution
421	return it->second->sample(seed);	7,128✔
422	}
423
424	//==============================================================================
425	// Helper function
426	//==============================================================================
427
428	UPtrDist distribution_from_xml(pugi::xml_node node)	33,634✔
429	{
430	if (!check_for_node(node, "type"))	33,634!
431	openmc::fatal_error("Distribution type must be specified.");	×
432
433	// Determine type of distribution
434	std::string type = get_node_value(node, "type", true, true);	33,634✔
435
436	// Allocate extension of Distribution
437	UPtrDist dist;	33,634✔
438	if (type == "uniform") {	33,634✔
439	dist = UPtrDist {new Uniform(node)};	256✔
440	} else if (type == "powerlaw") {	33,378✔
441	dist = UPtrDist {new PowerLaw(node)};	32✔
442	} else if (type == "maxwell") {	33,346✔
443	dist = UPtrDist {new Maxwell(node)};	64✔
444	} else if (type == "watt") {	33,282✔
445	dist = UPtrDist {new Watt(node)};	96✔
446	} else if (type == "normal") {	33,186!
447	dist = UPtrDist {new Normal(node)};	×
448	} else if (type == "discrete") {	33,186✔
449	dist = UPtrDist {new Discrete(node)};	25,853✔
450	} else if (type == "tabular") {	7,333✔
451	dist = UPtrDist {new Tabular(node)};	7,285✔
452	} else if (type == "mixture") {	48!
453	dist = UPtrDist {new Mixture(node)};	48✔
454	} else if (type == "muir") {	×
455	openmc::fatal_error(	×
456	"'muir' distributions are now specified using the openmc.stats.muir() "
457	"function in Python. Please regenerate your XML files.");
458	} else {
459	openmc::fatal_error("Invalid distribution type: " + type);	×
460	}
461	return dist;	67,268✔
462	}	33,634✔
463
464	} // namespace openmc

openmc-dev / openmc / 18537555145

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