19072640351

Committed 04 Nov 2025 02:49PM UTC coverage: 81.932% (+0.06%) from 81.872%

Build # 19072640351

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Pull #3413

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Commit Message

Merge 043dbf5f9 into bd76fc056

Pull Request Pull Request #3413: More interpolation types in Tabular.

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70.33

/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 if (temp == "log-linear") {
      interp_ = Interpolation::log_lin;
    } else if (temp == "linear-log") {
      interp_ = Interpolation::lin_log;
    } else if (temp == "log-log") {
      interp_ = Interpolation::log_log;
    } 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_));

  // 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]);
      } else if (interp_ == Interpolation::lin_log) {
        double m = (p_[i] - p_[i - 1]) / std::log(x_[i] / x_[i - 1]);
        c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]) +
                m * (x_[i] * (std::log(x_[i] / x_[i - 1]) - 1.0) + x_[i - 1]);
      } else if (interp_ == Interpolation::log_lin) {
        double m = std::log(p_[i] / p_[i - 1]) / (x_[i] - x_[i - 1]);
        c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]) *
                              exprel(m * (x_[i] - x_[i - 1]));
      } else if (interp_ == Interpolation::log_log) {
        double m = std::log((x_[i] * p_[i]) / (x_[i - 1] * p_[i - 1])) /
                   std::log(x_[i] / x_[i - 1]);
        c_[i] = c_[i - 1] + x_[i - 1] * p_[i - 1] *
                              std::log(x_[i] / x_[i - 1]) *
                              exprel(m * std::log(x_[i] / x_[i - 1]));
      } else {
        UNREACHABLE();
      }
    }
  }

  // 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 if (interp_ == Interpolation::lin_lin) {
    // 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;
    }
  } else if (interp_ == Interpolation::lin_log) {
    // Linear-Log interpolation
    double x_i1 = x_[i + 1];
    double p_i1 = p_[i + 1];

    double m = (p_i1 - p_i) / std::log(x_i1 / x_i);
    double a = p_i / m - 1;
    if (m > 0.0) {
      return x_i * ((c - c_i) / (m * x_i) + a) /
             lambert_w0(((c - c_i) / (m * x_i) + a) * std::exp(a));
    } else if (m < 0.0) {
      return x_i * ((c - c_i) / (m * x_i) + a) /
             lambert_wm1(((c - c_i) / (m * x_i) + a) * std::exp(a));
    } else {
      return x_i + (c - c_i) / p_i;
    }
  } else if (interp_ == Interpolation::log_lin) {
    // Log-linear interpolation
    double x_i1 = x_[i + 1];
    double p_i1 = p_[i + 1];

    double m = std::log(p_i1 / p_i) / (x_i1 - x_i);
    double f = (c - c_i) / p_i;
    return x_i + f * log1prel(m * f);
  } else if (interp_ == Interpolation::log_log) {
    // Log-Log interpolation
    double x_i1 = x_[i + 1];
    double p_i1 = p_[i + 1];

    double m = std::log((x_i1 * p_i1) / (x_i * p_i)) / std::log(x_i1 / x_i);
    double f = (c - c_i) / (p_i * x_i);
    return x_i * std::exp(f * log1prel(m * f));
  } else {
    UNREACHABLE();
  }
}

//==============================================================================
// 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)	27,747✔
24	{
25	auto params = get_node_array<double>(node, "parameters");	27,747✔
26	std::size_t n = params.size() / 2;	27,747✔
27
28	assign({params.data() + n, n});	27,747✔
29	}	27,747✔
30
31	DiscreteIndex::DiscreteIndex(span<const double> p)	107,483✔
32	{
33	assign(p);	107,483✔
34	}	107,483✔
35
36	void DiscreteIndex::assign(span<const double> p)	143,985✔
37	{
38	prob_.assign(p.begin(), p.end());	143,985✔
39
40	this->init_alias();	143,985✔
41	}	143,985✔
42
43	void DiscreteIndex::init_alias()	143,985✔
44	{
45	normalize();	143,985✔
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;	143,985✔
51	vector<size_t> small;	143,985✔
52
53	size_t n = prob_.size();	143,985✔
54
55	// Set and allocate memory
56	alias_.assign(n, 0);	143,985✔
57
58	// Fill large and small vectors based on 1/n
59	for (size_t i = 0; i < n; i++) {	1,953,618✔
60	prob_[i] *= n;	1,809,633✔
61	if (prob_[i] > 1.0) {	1,809,633✔
62	large.push_back(i);	265,341✔
63	} else {
64	small.push_back(i);	1,544,292✔
65	}
66	}
67
68	while (!large.empty() && !small.empty()) {	1,615,484✔
69	int j = small.back();	1,471,499✔
70	int k = large.back();	1,471,499✔
71
72	// Remove last element of small
73	small.pop_back();	1,471,499✔
74
75	// Update probability and alias based on Vose's algorithm
76	prob_[k] += prob_[j] - 1.0;	1,471,499✔
77	alias_[j] = k;	1,471,499✔
78
79	// Move large index to small vector, if it is no longer large
80	if (prob_[k] < 1.0) {	1,471,499✔
81	small.push_back(k);	256,986✔
82	large.pop_back();	256,986✔
83	}
84	}
85	}	143,985✔
86
87	size_t DiscreteIndex::sample(uint64_t* seed) const	71,999,146✔
88	{
89	// Alias sampling of discrete distribution
90	size_t n = prob_.size();	71,999,146✔
91	if (n > 1) {	71,999,146✔
92	size_t u = prn(seed) * n;	16,416,062✔
93	if (prn(seed) < prob_[u]) {	16,416,062✔
94	return u;	10,494,183✔
95	} else {
96	return alias_[u];	5,921,879✔
97	}
98	} else {
99	return 0;	55,583,084✔
100	}
101	}
102
103	void DiscreteIndex::normalize()	143,985✔
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);	143,985✔
109	for (auto& p_i : prob_) {	1,953,618✔
110	p_i /= integral_;	1,809,633✔
111	}
112	}	143,985✔
113
114	//==============================================================================
115	// Discrete implementation
116	//==============================================================================
117
118	Discrete::Discrete(pugi::xml_node node) : di_(node)	27,747✔
119	{
120	auto params = get_node_array<double>(node, "parameters");	27,747✔
121
122	std::size_t n = params.size() / 2;	27,747✔
123
124	x_.assign(params.begin(), params.begin() + n);	27,747✔
125	}	27,747✔
126
127	Discrete::Discrete(const double* x, const double* p, size_t n) : di_({p, n})	107,483✔
128	{
129
130	x_.assign(x, x + n);	107,483✔
131	}	107,483✔
132
133	double Discrete::sample(uint64_t* seed) const	66,637,818✔
134	{
135	return x_[di_.sample(seed)];	66,637,818✔
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	283,488✔
155	{
156	return a_ + prn(seed) * (b_ - a_);	283,488✔
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	12,907,370✔
215	{
216	return watt_spectrum(a_, b_, seed);	12,907,370✔
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);	×
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)	7,859✔
244	{
245	if (check_for_node(node, "interpolation")) {	7,859!
246	std::string temp = get_node_value(node, "interpolation");	7,859✔
247	if (temp == "histogram") {	7,859✔
248	interp_ = Interpolation::histogram;	7,795✔
249	} else if (temp == "linear-linear") {	64!
250	interp_ = Interpolation::lin_lin;	64✔
NEW 251	} else if (temp == "log-linear") {	×
NEW 252	interp_ = Interpolation::log_lin;	×
NEW 253	} else if (temp == "linear-log") {	×
NEW 254	interp_ = Interpolation::lin_log;	×
NEW 255	} else if (temp == "log-log") {	×
NEW 256	interp_ = Interpolation::log_log;	×
257	} else {
258	openmc::fatal_error(	×
259	"Unsupported interpolation type for distribution: " + temp);	×
260	}
261	} else {	7,859✔
262	interp_ = Interpolation::histogram;	×
263	}
264
265	// Read and initialize tabular distribution. If number of parameters is odd,
266	// add an extra zero for the 'p' array.
267	auto params = get_node_array<double>(node, "parameters");	7,859✔
268	if (params.size() % 2 != 0) {	7,859!
269	params.push_back(0.0);	×
270	}
271	std::size_t n = params.size() / 2;	7,859✔
272	const double* x = params.data();	7,859✔
273	const double* p = x + n;	7,859✔
274	init(x, p, n);	7,859✔
275	}	7,859✔
276
277	Tabular::Tabular(const double* x, const double* p, int n, Interpolation interp,	56,264,593✔
278	const double* c)	56,264,593✔
279	: interp_ {interp}	56,264,593✔
280	{
281	init(x, p, n, c);	56,264,593✔
282	}	56,264,593✔
283
284	void Tabular::init(	56,272,452✔
285	const double* x, const double* p, std::size_t n, const double* c)
286	{
287	// Copy x/p arrays into vectors
288	std::copy(x, x + n, std::back_inserter(x_));	56,272,452✔
289	std::copy(p, p + n, std::back_inserter(p_));	56,272,452✔
290
291	// Calculate cumulative distribution function
292	if (c) {	56,272,452✔
293	std::copy(c, c + n, std::back_inserter(c_));	56,264,593✔
294	} else {
295	c_.resize(n);	7,859✔
296	c_[0] = 0.0;	7,859✔
297	for (int i = 1; i < n; ++i) {	97,380✔
298	if (interp_ == Interpolation::histogram) {	89,521✔
299	c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]);	89,393✔
300	} else if (interp_ == Interpolation::lin_lin) {	128!
301	c_[i] = c_[i - 1] + 0.5 * (p_[i - 1] + p_[i]) * (x_[i] - x_[i - 1]);	128✔
NEW 302	} else if (interp_ == Interpolation::lin_log) {	×
NEW 303	double m = (p_[i] - p_[i - 1]) / std::log(x_[i] / x_[i - 1]);	×
NEW 304	c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]) +	×
NEW 305	m * (x_[i] * (std::log(x_[i] / x_[i - 1]) - 1.0) + x_[i - 1]);	×
NEW 306	} else if (interp_ == Interpolation::log_lin) {	×
NEW 307	double m = std::log(p_[i] / p_[i - 1]) / (x_[i] - x_[i - 1]);	×
NEW 308	c_[i] = c_[i - 1] + p_[i - 1] * (x_[i] - x_[i - 1]) *	×
NEW 309	exprel(m * (x_[i] - x_[i - 1]));	×
NEW 310	} else if (interp_ == Interpolation::log_log) {	×
NEW 311	double m = std::log((x_[i] * p_[i]) / (x_[i - 1] * p_[i - 1])) /	×
NEW 312	std::log(x_[i] / x_[i - 1]);	×
NEW 313	c_[i] = c_[i - 1] + x_[i - 1] * p_[i - 1] *	×
NEW 314	std::log(x_[i] / x_[i - 1]) *	×
NEW 315	exprel(m * std::log(x_[i] / x_[i - 1]));	×
316	} else {
NEW 317	UNREACHABLE();	×
318	}
319	}
320	}
321
322	// Normalize density and distribution functions. Note that we save the
323	// integral of the distribution so that if it is used as part of another
324	// distribution (e.g., Mixture), we know its relative strength.
325	integral_ = c_[n - 1];	56,272,452✔
326	for (int i = 0; i < n; ++i) {	803,597,605✔
327	p_[i] = p_[i] / integral_;	747,325,153✔
328	c_[i] = c_[i] / integral_;	747,325,153✔
329	}
330	}	56,272,452✔
331
332	double Tabular::sample(uint64_t* seed) const	701,711,476✔
333	{
334	// Sample value of CDF
335	double c = prn(seed);	701,711,476✔
336
337	// Find first CDF bin which is above the sampled value
338	double c_i = c_[0];	701,711,476✔
339	int i;
340	std::size_t n = c_.size();	701,711,476✔
341	for (i = 0; i < n - 1; ++i) {	2,147,483,647!
342	if (c <= c_[i + 1])	2,147,483,647✔
343	break;	701,711,476✔
344	c_i = c_[i + 1];	1,974,014,207✔
345	}
346
347	// Determine bounding PDF values
348	double x_i = x_[i];	701,711,476✔
349	double p_i = p_[i];	701,711,476✔
350
351	if (interp_ == Interpolation::histogram) {	701,711,476✔
352	// Histogram interpolation
353	if (p_i > 0.0) {	3,421,748!
354	return x_i + (c - c_i) / p_i;	3,421,748✔
355	} else {
356	return x_i;	×
357	}
358	} else if (interp_ == Interpolation::lin_lin) {	698,289,728!
359	// Linear-linear interpolation
360	double x_i1 = x_[i + 1];	698,289,728✔
361	double p_i1 = p_[i + 1];	698,289,728✔
362
363	double m = (p_i1 - p_i) / (x_i1 - x_i);	698,289,728✔
364	if (m == 0.0) {	698,289,728✔
365	return x_i + (c - c_i) / p_i;	342,607,172✔
366	} else {
367	return x_i +
368	(std::sqrt(std::max(0.0, p_i * p_i + 2 * m * (c - c_i))) - p_i) /	355,682,556✔
369	m;	355,682,556✔
370	}
NEW 371	} else if (interp_ == Interpolation::lin_log) {	×
372	// Linear-Log interpolation
NEW 373	double x_i1 = x_[i + 1];	×
NEW 374	double p_i1 = p_[i + 1];	×
375
NEW 376	double m = (p_i1 - p_i) / std::log(x_i1 / x_i);	×
NEW 377	double a = p_i / m - 1;	×
NEW 378	if (m > 0.0) {	×
NEW 379	return x_i * ((c - c_i) / (m * x_i) + a) /	×
NEW 380	lambert_w0(((c - c_i) / (m * x_i) + a) * std::exp(a));	×
NEW 381	} else if (m < 0.0) {	×
NEW 382	return x_i * ((c - c_i) / (m * x_i) + a) /	×
NEW 383	lambert_wm1(((c - c_i) / (m * x_i) + a) * std::exp(a));	×
384	} else {
NEW 385	return x_i + (c - c_i) / p_i;	×
386	}
NEW 387	} else if (interp_ == Interpolation::log_lin) {	×
388	// Log-linear interpolation
NEW 389	double x_i1 = x_[i + 1];	×
NEW 390	double p_i1 = p_[i + 1];	×
391
NEW 392	double m = std::log(p_i1 / p_i) / (x_i1 - x_i);	×
NEW 393	double f = (c - c_i) / p_i;	×
NEW 394	return x_i + f * log1prel(m * f);	×
NEW 395	} else if (interp_ == Interpolation::log_log) {	×
396	// Log-Log interpolation
NEW 397	double x_i1 = x_[i + 1];	×
NEW 398	double p_i1 = p_[i + 1];	×
399
NEW 400	double m = std::log((x_i1 * p_i1) / (x_i * p_i)) / std::log(x_i1 / x_i);	×
NEW 401	double f = (c - c_i) / (p_i * x_i);	×
NEW 402	return x_i * std::exp(f * log1prel(m * f));	×
403	} else {
NEW 404	UNREACHABLE();	×
405	}
406	}
407
408	//==============================================================================
409	// Equiprobable implementation
410	//==============================================================================
411
412	double Equiprobable::sample(uint64_t* seed) const	×
413	{
414	std::size_t n = x_.size();	×
415
416	double r = prn(seed);	×
417	int i = std::floor((n - 1) * r);	×
418
419	double xl = x_[i];	×
420	double xr = x_[i + i];	×
421	return xl + ((n - 1) * r - i) * (xr - xl);	×
422	}
423
424	//==============================================================================
425	// Mixture implementation
426	//==============================================================================
427
428	Mixture::Mixture(pugi::xml_node node)	48✔
429	{
430	double cumsum = 0.0;	48✔
431	for (pugi::xml_node pair : node.children("pair")) {	192✔
432	// Check that required data exists
433	if (!pair.attribute("probability"))	144!
434	fatal_error("Mixture pair element does not have probability.");	×
435	if (!pair.child("dist"))	144!
436	fatal_error("Mixture pair element does not have a distribution.");	×
437
438	// cummulative sum of probabilities
439	double p = std::stod(pair.attribute("probability").value());	144✔
440
441	// Save cummulative probability and distribution
442	auto dist = distribution_from_xml(pair.child("dist"));	144✔
443	cumsum += p * dist->integral();	144✔
444
445	distribution_.push_back(std::make_pair(cumsum, std::move(dist)));	144✔
446	}	144✔
447
448	// Save integral of distribution
449	integral_ = cumsum;	48✔
450
451	// Normalize cummulative probabilities to 1
452	for (auto& pair : distribution_) {	192✔
453	pair.first /= cumsum;	144✔
454	}
455	}	48✔
456
457	double Mixture::sample(uint64_t* seed) const	3,564✔
458	{
459	// Sample value of CDF
460	const double p = prn(seed);	3,564✔
461
462	// find matching distribution
463	const auto it = std::lower_bound(distribution_.cbegin(), distribution_.cend(),	3,564✔
464	p, [](const DistPair& pair, double p) { return pair.first < p; });	7,128✔
465
466	// This should not happen. Catch it
467	assert(it != distribution_.cend());	2,916!
468
469	// Sample the chosen distribution
470	return it->second->sample(seed);	7,128✔
471	}
472
473	//==============================================================================
474	// Helper function
475	//==============================================================================
476
477	UPtrDist distribution_from_xml(pugi::xml_node node)	36,091✔
478	{
479	if (!check_for_node(node, "type"))	36,091!
480	openmc::fatal_error("Distribution type must be specified.");	×
481
482	// Determine type of distribution
483	std::string type = get_node_value(node, "type", true, true);	36,091✔
484
485	// Allocate extension of Distribution
486	UPtrDist dist;	36,091✔
487	if (type == "uniform") {	36,091✔
488	dist = UPtrDist {new Uniform(node)};	256✔
489	} else if (type == "powerlaw") {	35,835✔
490	dist = UPtrDist {new PowerLaw(node)};	32✔
491	} else if (type == "maxwell") {	35,803✔
492	dist = UPtrDist {new Maxwell(node)};	64✔
493	} else if (type == "watt") {	35,739✔
494	dist = UPtrDist {new Watt(node)};	96✔
495	} else if (type == "normal") {	35,643!
496	dist = UPtrDist {new Normal(node)};	×
497	} else if (type == "discrete") {	35,643✔
498	dist = UPtrDist {new Discrete(node)};	27,736✔
499	} else if (type == "tabular") {	7,907✔
500	dist = UPtrDist {new Tabular(node)};	7,859✔
501	} else if (type == "mixture") {	48!
502	dist = UPtrDist {new Mixture(node)};	48✔
503	} else if (type == "muir") {	×
504	openmc::fatal_error(	×
505	"'muir' distributions are now specified using the openmc.stats.muir() "
506	"function in Python. Please regenerate your XML files.");
507	} else {
508	openmc::fatal_error("Invalid distribution type: " + type);	×
509	}
510	return dist;	72,182✔
511	}	36,091✔
512
513	} // namespace openmc

openmc-dev / openmc / 19072640351

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