22593927413

Committed 02 Mar 2026 08:16PM UTC coverage: 81.339% (-0.2%) from 81.508%

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Pull #3550

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Merge 1f5e24e59 into 823b4c96c

Pull Request Pull Request #3550: [Point Detector] Add distribution get_pdf functionality

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70.75

/src/secondary_thermal.cpp

#include "openmc/secondary_thermal.h"

#include "openmc/hdf5_interface.h"
#include "openmc/math_functions.h"
#include "openmc/random_lcg.h"
#include "openmc/search.h"
#include "openmc/vector.h"

#include "openmc/tensor.h"

#include <cassert>
#include <cmath> // for log, exp

namespace openmc {

//==============================================================================
// CoherentElasticAE implementation
//==============================================================================

CoherentElasticAE::CoherentElasticAE(const CoherentElasticXS& xs) : xs_ {xs}
{
  const auto& factors = xs_.factors();
  auto n = factors.size();
  factors_diff_ = tensor::zeros<double>({n});
  factors_diff_.slice(0) = factors[0];
  for (int i = 1; i < n; ++i) {
    factors_diff_.slice(i) = factors[i] - factors[i - 1];
  }
}

void CoherentElasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  // Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
  E_out = E_in;
  const auto& energies {xs_.bragg_edges()};
  assert(E_in >= energies.front());

  const int i = lower_bound_index(energies.begin(), energies.end(), E_in);

  // Sample a Bragg edge between 1 and i
  // E[0] < E_in < E[i+1] -> can scatter in bragg edges 0..i
  const auto& factors = xs_.factors();
  const double prob = prn(seed) * factors[i];

  const int k = std::lower_bound(factors.begin(), factors.begin() + i, prob) -
                factors.begin();

  // Characteristic scattering cosine for this Bragg edge (ENDF-102, Eq. 7-2)
  mu = 1.0 - 2.0 * energies[k] / E_in;
}

double CoherentElasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  // Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)

  double pdf;
  E_out = E_in;
  const auto energies =
    tensor::Tensor<double>(xs_.bragg_edges().data(), xs_.bragg_edges().size());
  const auto& factors = xs_.factors();

  if (E_in < energies.front() || E_in > energies.back()) {
    return 0;
  }

  const int n = upper_bound_index(energies.begin(), energies.end(), E_in);
  double E = 0.5 * (1 - mu) * E_in;
  double C = 0.5 * E_in / factors[n];

  return C * get_pdf_discrete(
               energies.slice(0, n), factors_diff_.slice(0, n), E, 0, E_in);
}

//==============================================================================
// IncoherentElasticAE implementation
//==============================================================================

IncoherentElasticAE::IncoherentElasticAE(hid_t group)
{
  read_dataset(group, "debye_waller", debye_waller_);
}

void IncoherentElasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  E_out = E_in;

  // Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
  double c = 2 * E_in * debye_waller_;
  mu = std::log(1.0 + prn(seed) * (std::exp(2.0 * c) - 1)) / c - 1.0;
}
double IncoherentElasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  E_out = E_in;

  // Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
  double c = 2 * E_in * debye_waller_;
  double A = c / (1 - std::exp(-2.0 * c)); // normalization factor
  return A * std::exp(-c * (1 - mu));
}

//==============================================================================
// IncoherentElasticAEDiscrete implementation
//==============================================================================

IncoherentElasticAEDiscrete::IncoherentElasticAEDiscrete(
  hid_t group, const vector<double>& energy)
  : energy_ {energy}
{
  read_dataset(group, "mu_out", mu_out_);
}

void IncoherentElasticAEDiscrete::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  // Get index and interpolation factor for elastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);

  // Interpolate between two discrete cosines corresponding to neighboring
  // incoming energies.

  // Sample outgoing cosine bin
  int n_mu = mu_out_.shape(1);
  int k = prn(seed) * n_mu;

  // Rather than use the sampled discrete mu directly, it is smeared over
  // a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
  // discrete mu value itself.

  // Interpolate kth mu value between distributions at energies i and i+1
  mu = mu_out_(i, k) + f * (mu_out_(i + 1, k) - mu_out_(i, k));

  // Inteprolate (k-1)th mu value between distributions at energies i and i+1.
  // When k==0, pick a value that will smear the cosine out to a minimum of -1.
  double mu_left = (k == 0) ? -1.0 - (mu + 1.0)
                            : mu_out_(i, k - 1) +
                                f * (mu_out_(i + 1, k - 1) - mu_out_(i, k - 1));

  // Inteprolate (k+1)th mu value between distributions at energies i and i+1.
  // When k is the last discrete value, pick a value that will smear the cosine
  // out to a maximum of 1.
  double mu_right =
    (k == n_mu - 1)
      ? 1.0 + (1.0 - mu)
      : mu_out_(i, k + 1) + f * (mu_out_(i + 1, k + 1) - mu_out_(i, k + 1));

  // Smear cosine
  mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);

  // Energy doesn't change in elastic scattering
  E_out = E_in;
}

double IncoherentElasticAEDiscrete::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  // Get index and interpolation factor for elastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);
  // Energy doesn't change in elastic scattering
  E_out = E_in;

  double pdf = 0.0;
  pdf += f * get_pdf_discrete(mu_out_.slice(i + 1, tensor::all), mu);
  pdf += (1 - f) * get_pdf_discrete(mu_out_.slice(i, tensor::all), mu);
  return pdf;
}

//==============================================================================
// IncoherentInelasticAEDiscrete implementation
//==============================================================================

IncoherentInelasticAEDiscrete::IncoherentInelasticAEDiscrete(
  hid_t group, const vector<double>& energy)
  : energy_ {energy}
{
  read_dataset(group, "energy_out", energy_out_);
  read_dataset(group, "mu_out", mu_out_);
  read_dataset(group, "skewed", skewed_);
}

void IncoherentInelasticAEDiscrete::sample_params(
  double E_in, double& E_out, int& j, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);

  // Now that we have an incoming energy bin, we need to determine the outgoing
  // energy bin. This will depend on whether the outgoing energy distribution is
  // skewed. If it is skewed, then the first two and last two bins have lower
  // probabilities than the other bins (0.1 for the first and last bins and 0.4
  // for the second and second to last bins, relative to a normal bin
  // probability of 1). Otherwise, each bin is equally probable.

  int n = energy_out_.shape(1);
  if (!skewed_) {
    // All bins equally likely
    j = prn(seed) * n;
  } else {
    // Distribution skewed away from edge points
    double r = prn(seed) * (n - 3);
    if (r > 1.0) {
      // equally likely N-4 middle bins
      j = r + 1;
    } else if (r > 0.6) {
      // second to last bin has relative probability of 0.4
      j = n - 2;
    } else if (r > 0.5) {
      // last bin has relative probability of 0.1
      j = n - 1;
    } else if (r > 0.1) {
      // second bin has relative probability of 0.4
      j = 1;
    } else {
      // first bin has relative probability of 0.1
      j = 0;
    }
  }

  // Determine outgoing energy corresponding to E_in[i] and E_in[i+1]
  double E_ij = energy_out_(i, j);
  double E_i1j = energy_out_(i + 1, j);

  // Outgoing energy
  E_out = (1 - f) * E_ij + f * E_i1j;
}

void IncoherentInelasticAEDiscrete::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);

  int j;
  sample_params(E_in, E_out, j, seed);

  // Sample outgoing cosine bin
  int m = mu_out_.shape(2);
  int k = prn(seed) * m;

  // Determine outgoing cosine corresponding to E_in[i] and E_in[i+1]
  double mu_ijk = mu_out_(i, j, k);
  double mu_i1jk = mu_out_(i + 1, j, k);

  // Cosine of angle between incoming and outgoing neutron
  mu = (1 - f) * mu_ijk + f * mu_i1jk;
}

double IncoherentInelasticAEDiscrete::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);
  int j;
  sample_params(E_in, E_out, j, seed);

  double pdf = 0.0;
  pdf += f * get_pdf_discrete(mu_out_.slice(i + 1, j, tensor::all), mu);
  pdf += (1 - f) * get_pdf_discrete(mu_out_.slice(i, j, tensor::all), mu);
  return pdf;
}

//==============================================================================
// IncoherentInelasticAE implementation
//==============================================================================

IncoherentInelasticAE::IncoherentInelasticAE(hid_t group)
{
  // Read correlated angle-energy distribution
  CorrelatedAngleEnergy dist {group};

  // Copy incident energies
  energy_ = dist.energy();

  // Convert to S(a,b) native format
  for (const auto& edist : dist.distribution()) {
    // Create temporary distribution
    DistEnergySab d;

    // Copy outgoing energy distribution
    d.n_e_out = edist.e_out.size();
    d.e_out = edist.e_out;
    d.e_out_pdf = edist.p;
    d.e_out_cdf = edist.c;

    for (int j = 0; j < d.n_e_out; ++j) {
      auto adist = dynamic_cast<Tabular*>(edist.angle[j].get());
      if (adist) {
        // On first pass, allocate space for angles
        if (j == 0) {
          auto n_mu = adist->x().size();
          d.mu = tensor::Tensor<double>({d.n_e_out, n_mu});
        }

        // Copy outgoing angles
        tensor::View<double> mu_j = d.mu.slice(j);
        std::copy(adist->x().begin(), adist->x().end(), mu_j.begin());
      }
    }

    distribution_.emplace_back(std::move(d));
  }
}

void IncoherentInelasticAE::sample_params(
  double E_in, double& E_out, double& f, int& l, int& j, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f0;
  get_energy_index(energy_, E_in, i, f0);

  // Pick closer energy based on interpolation factor
  l = f0 > 0.5 ? i + 1 : i;

  // Determine outgoing energy bin
  // (First reset n_energy_out to the right value)
  int n = distribution_[l].n_e_out;
  double r1 = prn(seed);
  double c_j = distribution_[l].e_out_cdf[0];
  double c_j1;
  for (j = 0; j < n - 1; ++j) {
    c_j1 = distribution_[l].e_out_cdf[j + 1];
    if (r1 < c_j1)
      break;
    c_j = c_j1;
  }

  // check to make sure j is <= n_energy_out - 2
  j = std::min(j, n - 2);

  // Get the data to interpolate between
  double E_l_j = distribution_[l].e_out[j];
  double p_l_j = distribution_[l].e_out_pdf[j];

  // Next part assumes linear-linear interpolation in standard
  double E_l_j1 = distribution_[l].e_out[j + 1];
  double p_l_j1 = distribution_[l].e_out_pdf[j + 1];

  // Find secondary energy (variable E)
  double frac = (p_l_j1 - p_l_j) / (E_l_j1 - E_l_j);
  if (frac == 0.0) {
    E_out = E_l_j + (r1 - c_j) / p_l_j;
  } else {
    E_out = E_l_j +
            (std::sqrt(std::max(0.0, p_l_j * p_l_j + 2.0 * frac * (r1 - c_j))) -
              p_l_j) /
              frac;
  }

  // Adjustment of outgoing energy
  double E_l = energy_[l];
  if (E_out < 0.5 * E_l) {
    E_out *= 2.0 * E_in / E_l - 1.0;
  } else {
    E_out += E_in - E_l;
  }

  f = (r1 - c_j) / (c_j1 - c_j);
}
void IncoherentInelasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  double f;
  int l, j;
  sample_params(E_in, E_out, f, l, j, seed);

  // Sample outgoing cosine bin
  int n_mu = distribution_[l].mu.shape(1);
  std::size_t k = prn(seed) * n_mu;

  // Rather than use the sampled discrete mu directly, it is smeared over
  // a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
  // discrete mu value itself.
  const auto& mu_l = distribution_[l].mu;

  // Interpolate kth mu value between distributions at energies j and j+1
  mu = mu_l(j, k) + f * (mu_l(j + 1, k) - mu_l(j, k));

  // Inteprolate (k-1)th mu value between distributions at energies j and j+1.
  // When k==0, pick a value that will smear the cosine out to a minimum of -1.
  double mu_left =
    (k == 0)
      ? mu_left = -1.0 - (mu + 1.0)
      : mu_left = mu_l(j, k - 1) + f * (mu_l(j + 1, k - 1) - mu_l(j, k - 1));

  // Inteprolate (k+1)th mu value between distributions at energies j and j+1.
  // When k is the last discrete value, pick a value that will smear the cosine
  // out to a maximum of 1.
  double mu_right =
    (k == n_mu - 1)
      ? mu_right = 1.0 + (1.0 - mu)
      : mu_right = mu_l(j, k + 1) + f * (mu_l(j + 1, k + 1) - mu_l(j, k + 1));

  // Smear cosine
  mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);
}

double IncoherentInelasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  double f;
  int l, j;
  sample_params(E_in, E_out, f, l, j, seed);

  int n_mu = distribution_[l].mu.shape()[1];
  const auto& mu_l = distribution_[l].mu;

  double pdf = 0.0;
  pdf += f * get_pdf_discrete(mu_l.slice(j + 1, tensor::all), mu);
  pdf += (1 - f) * get_pdf_discrete(mu_l.slice(j, tensor::all), mu);
  return pdf;
}

//==============================================================================
// MixedElasticAE implementation
//==============================================================================

MixedElasticAE::MixedElasticAE(
  hid_t group, const CoherentElasticXS& coh_xs, const Function1D& incoh_xs)
  : coherent_dist_(coh_xs), coherent_xs_(coh_xs), incoherent_xs_(incoh_xs)
{
  // Read incoherent elastic distribution
  hid_t incoherent_group = open_group(group, "incoherent");
  std::string temp;
  read_attribute(incoherent_group, "type", temp);
  if (temp == "incoherent_elastic") {
    incoherent_dist_ = make_unique<IncoherentElasticAE>(incoherent_group);
  } else if (temp == "incoherent_elastic_discrete") {
    auto xs = dynamic_cast<const Tabulated1D*>(&incoh_xs);
    incoherent_dist_ =
      make_unique<IncoherentElasticAEDiscrete>(incoherent_group, xs->x());
  }
  close_group(incoherent_group);
}

const AngleEnergy& MixedElasticAE::sample_dist(
  double E_in, uint64_t* seed) const
{
  // Evaluate coherent and incoherent elastic cross sections
  double xs_coh = coherent_xs_(E_in);
  double xs_incoh = incoherent_xs_(E_in);

  if (prn(seed) * (xs_coh + xs_incoh) < xs_coh) {
    return coherent_dist_;
  } else {
    return *incoherent_dist_;
  }
}

void MixedElasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  sample_dist(E_in, seed).sample(E_in, E_out, mu, seed);
}

double MixedElasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  return sample_dist(E_in, seed).sample_energy_and_pdf(E_in, mu, E_out, seed);
}

} // namespace openmc

1	#include "openmc/secondary_thermal.h"
2
3	#include "openmc/hdf5_interface.h"
4	#include "openmc/math_functions.h"
5	#include "openmc/random_lcg.h"
6	#include "openmc/search.h"
7	#include "openmc/vector.h"
8
9	#include "openmc/tensor.h"
10
11	#include <cassert>
12	#include <cmath> // for log, exp
13
14	namespace openmc {
15
16	//==============================================================================
17	// CoherentElasticAE implementation
18	//==============================================================================
19
20	CoherentElasticAE::CoherentElasticAE(const CoherentElasticXS& xs) : xs_ {xs}	134✔
21	{
22	const auto& factors = xs_.factors();	134✔
23	auto n = factors.size();	134✔
24	factors_diff_ = tensor::zeros<double>({n});	134✔
25	factors_diff_.slice(0) = factors[0];	134✔
26	for (int i = 1; i < n; ++i) {	19,878✔
27	factors_diff_.slice(i) = factors[i] - factors[i - 1];	39,488✔
28	}
29	}	134✔
30
31	void CoherentElasticAE::sample(	178,013✔
32	double E_in, double& E_out, double& mu, uint64_t* seed) const
33	{
34	// Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
35	E_out = E_in;	178,013✔
36	const auto& energies {xs_.bragg_edges()};	178,013!
37	assert(E_in >= energies.front());	178,013!
38
39	const int i = lower_bound_index(energies.begin(), energies.end(), E_in);	178,013✔
40
41	// Sample a Bragg edge between 1 and i
42	// E[0] < E_in < E[i+1] -> can scatter in bragg edges 0..i
43	const auto& factors = xs_.factors();	178,013✔
44	const double prob = prn(seed) * factors[i];	178,013✔
45
46	const int k = std::lower_bound(factors.begin(), factors.begin() + i, prob) -	178,013✔
47	factors.begin();	178,013✔
48
49	// Characteristic scattering cosine for this Bragg edge (ENDF-102, Eq. 7-2)
50	mu = 1.0 - 2.0 * energies[k] / E_in;	178,013✔
51	}	178,013✔
52
NEW 53	double CoherentElasticAE::sample_energy_and_pdf(	×
54	double E_in, double mu, double& E_out, uint64_t* seed) const
55	{
56	// Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
57
NEW 58	double pdf;	×
NEW 59	E_out = E_in;	×
NEW 60	const auto energies =	×
NEW 61	tensor::Tensor<double>(xs_.bragg_edges().data(), xs_.bragg_edges().size());	×
NEW 62	const auto& factors = xs_.factors();	×
63
NEW 64	if (E_in < energies.front() \|\| E_in > energies.back()) {	×
65	return 0;
66	}
67
NEW 68	const int n = upper_bound_index(energies.begin(), energies.end(), E_in);	×
NEW 69	double E = 0.5 * (1 - mu) * E_in;	×
NEW 70	double C = 0.5 * E_in / factors[n];	×
71
NEW 72	return C * get_pdf_discrete(	×
NEW 73	energies.slice(0, n), factors_diff_.slice(0, n), E, 0, E_in);	×
NEW 74	}	×
75
76	//==============================================================================
77	// IncoherentElasticAE implementation
78	//==============================================================================
79
80	IncoherentElasticAE::IncoherentElasticAE(hid_t group)	×
81	{
82	read_dataset(group, "debye_waller", debye_waller_);	×
83	}	×
84
85	void IncoherentElasticAE::sample(	×
86	double E_in, double& E_out, double& mu, uint64_t* seed) const
87	{
NEW 88	E_out = E_in;	×
89
90	// Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
91	double c = 2 * E_in * debye_waller_;	×
92	mu = std::log(1.0 + prn(seed) * (std::exp(2.0 * c) - 1)) / c - 1.0;	×
NEW 93	}	×
NEW 94	double IncoherentElasticAE::sample_energy_and_pdf(	×
95	double E_in, double mu, double& E_out, uint64_t* seed) const
96	{
97	E_out = E_in;	×
98
99	// Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
NEW 100	double c = 2 * E_in * debye_waller_;	×
NEW 101	double A = c / (1 - std::exp(-2.0 * c)); // normalization factor	×
NEW 102	return A * std::exp(-c * (1 - mu));	×
103	}
104
105	//==============================================================================
106	// IncoherentElasticAEDiscrete implementation
107	//==============================================================================
108
109	IncoherentElasticAEDiscrete::IncoherentElasticAEDiscrete(	44✔
110	hid_t group, const vector<double>& energy)	44✔
111	: energy_ {energy}	44✔
112	{
113	read_dataset(group, "mu_out", mu_out_);	44✔
114	}	44✔
115
116	void IncoherentElasticAEDiscrete::sample(	1,342✔
117	double E_in, double& E_out, double& mu, uint64_t* seed) const
118	{
119	// Get index and interpolation factor for elastic grid
120	int i;	1,342✔
121	double f;	1,342✔
122	get_energy_index(energy_, E_in, i, f);	1,342✔
123
124	// Interpolate between two discrete cosines corresponding to neighboring
125	// incoming energies.
126
127	// Sample outgoing cosine bin
128	int n_mu = mu_out_.shape(1);	1,342!
129	int k = prn(seed) * n_mu;	1,342✔
130
131	// Rather than use the sampled discrete mu directly, it is smeared over
132	// a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
133	// discrete mu value itself.
134
135	// Interpolate kth mu value between distributions at energies i and i+1
136	mu = mu_out_(i, k) + f * (mu_out_(i + 1, k) - mu_out_(i, k));	1,342✔
137
138	// Inteprolate (k-1)th mu value between distributions at energies i and i+1.
139	// When k==0, pick a value that will smear the cosine out to a minimum of -1.
140	double mu_left = (k == 0) ? -1.0 - (mu + 1.0)	1,342✔
141	: mu_out_(i, k - 1) +	990✔
142	f * (mu_out_(i + 1, k - 1) - mu_out_(i, k - 1));	990✔
143
144	// Inteprolate (k+1)th mu value between distributions at energies i and i+1.
145	// When k is the last discrete value, pick a value that will smear the cosine
146	// out to a maximum of 1.
147	double mu_right =	1,342✔
148	(k == n_mu - 1)	1,342✔
149	? 1.0 + (1.0 - mu)	1,342✔
150	: mu_out_(i, k + 1) + f * (mu_out_(i + 1, k + 1) - mu_out_(i, k + 1));	990✔
151
152	// Smear cosine
153	mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);	1,947✔
154
155	// Energy doesn't change in elastic scattering
156	E_out = E_in;	1,342✔
157	}	1,342✔
158
NEW 159	double IncoherentElasticAEDiscrete::sample_energy_and_pdf(	×
160	double E_in, double mu, double& E_out, uint64_t* seed) const
161	{
162	// Get index and interpolation factor for elastic grid
NEW 163	int i;	×
NEW 164	double f;	×
NEW 165	get_energy_index(energy_, E_in, i, f);	×
166	// Energy doesn't change in elastic scattering
NEW 167	E_out = E_in;	×
168
NEW 169	double pdf = 0.0;	×
NEW 170	pdf += f * get_pdf_discrete(mu_out_.slice(i + 1, tensor::all), mu);	×
NEW 171	pdf += (1 - f) * get_pdf_discrete(mu_out_.slice(i, tensor::all), mu);	×
NEW 172	return pdf;	×
173	}
174
175	//==============================================================================
176	// IncoherentInelasticAEDiscrete implementation
177	//==============================================================================
178
179	IncoherentInelasticAEDiscrete::IncoherentInelasticAEDiscrete(	1,240✔
180	hid_t group, const vector<double>& energy)	1,240✔
181	: energy_ {energy}	1,240✔
182	{
183	read_dataset(group, "energy_out", energy_out_);	1,240✔
184	read_dataset(group, "mu_out", mu_out_);	1,240✔
185	read_dataset(group, "skewed", skewed_);	1,240✔
186	}	1,240✔
187
188	void IncoherentInelasticAEDiscrete::sample_params(	123,683,823✔
189	double E_in, double& E_out, int& j, uint64_t* seed) const
190	{
191	// Get index and interpolation factor for inelastic grid
192	int i;	123,683,823✔
193	double f;	123,683,823✔
194	get_energy_index(energy_, E_in, i, f);	123,683,823✔
195
196	// Now that we have an incoming energy bin, we need to determine the outgoing
197	// energy bin. This will depend on whether the outgoing energy distribution is
198	// skewed. If it is skewed, then the first two and last two bins have lower
199	// probabilities than the other bins (0.1 for the first and last bins and 0.4
200	// for the second and second to last bins, relative to a normal bin
201	// probability of 1). Otherwise, each bin is equally probable.
202
203	int n = energy_out_.shape(1);	123,683,823!
204	if (!skewed_) {	123,683,823!
205	// All bins equally likely
206	j = prn(seed) * n;	×
207	} else {
208	// Distribution skewed away from edge points
209	double r = prn(seed) * (n - 3);	123,683,823✔
210	if (r > 1.0) {	123,683,823✔
211	// equally likely N-4 middle bins
212	j = r + 1;	121,650,936✔
213	} else if (r > 0.6) {	2,032,887✔
214	// second to last bin has relative probability of 0.4
215	j = n - 2;	806,605✔
216	} else if (r > 0.5) {	1,226,282✔
217	// last bin has relative probability of 0.1
218	j = n - 1;	203,402✔
219	} else if (r > 0.1) {	1,022,880✔
220	// second bin has relative probability of 0.4
221	j = 1;	819,261✔
222	} else {
223	// first bin has relative probability of 0.1
224	j = 0;	203,619✔
225	}
226	}
227
228	// Determine outgoing energy corresponding to E_in[i] and E_in[i+1]
229	double E_ij = energy_out_(i, j);	123,683,823✔
230	double E_i1j = energy_out_(i + 1, j);	123,683,823✔
231
232	// Outgoing energy
233	E_out = (1 - f) * E_ij + f * E_i1j;	123,683,823✔
234	}	123,683,823✔
235
236	void IncoherentInelasticAEDiscrete::sample(	123,683,823✔
237	double E_in, double& E_out, double& mu, uint64_t* seed) const
238	{
239	// Get index and interpolation factor for inelastic grid
240	int i;	123,683,823✔
241	double f;	123,683,823✔
242	get_energy_index(energy_, E_in, i, f);	123,683,823✔
243
244	int j;	123,683,823✔
245	sample_params(E_in, E_out, j, seed);	123,683,823✔
246
247	// Sample outgoing cosine bin
248	int m = mu_out_.shape(2);	123,683,823!
249	int k = prn(seed) * m;	123,683,823✔
250
251	// Determine outgoing cosine corresponding to E_in[i] and E_in[i+1]
252	double mu_ijk = mu_out_(i, j, k);	123,683,823✔
253	double mu_i1jk = mu_out_(i + 1, j, k);	123,683,823✔
254
255	// Cosine of angle between incoming and outgoing neutron
256	mu = (1 - f) * mu_ijk + f * mu_i1jk;	123,683,823✔
257	}	123,683,823✔
258
NEW 259	double IncoherentInelasticAEDiscrete::sample_energy_and_pdf(	×
260	double E_in, double mu, double& E_out, uint64_t* seed) const
261	{
262	// Get index and interpolation factor for inelastic grid
NEW 263	int i;	×
NEW 264	double f;	×
NEW 265	get_energy_index(energy_, E_in, i, f);	×
NEW 266	int j;	×
NEW 267	sample_params(E_in, E_out, j, seed);	×
268
NEW 269	double pdf = 0.0;	×
NEW 270	pdf += f * get_pdf_discrete(mu_out_.slice(i + 1, j, tensor::all), mu);	×
NEW 271	pdf += (1 - f) * get_pdf_discrete(mu_out_.slice(i, j, tensor::all), mu);	×
NEW 272	return pdf;	×
273	}
274
275	//==============================================================================
276	// IncoherentInelasticAE implementation
277	//==============================================================================
278
279	IncoherentInelasticAE::IncoherentInelasticAE(hid_t group)	44✔
280	{
281	// Read correlated angle-energy distribution
282	CorrelatedAngleEnergy dist {group};	44✔
283
284	// Copy incident energies
285	energy_ = dist.energy();	44✔
286
287	// Convert to S(a,b) native format
288	for (const auto& edist : dist.distribution()) {	176✔
289	// Create temporary distribution
290	DistEnergySab d;	132✔
291
292	// Copy outgoing energy distribution
293	d.n_e_out = edist.e_out.size();	132✔
294	d.e_out = edist.e_out;	132✔
295	d.e_out_pdf = edist.p;	132✔
296	d.e_out_cdf = edist.c;	132✔
297
298	for (int j = 0; j < d.n_e_out; ++j) {	660✔
299	auto adist = dynamic_cast<Tabular*>(edist.angle[j].get());	528!
300	if (adist) {	528!
301	// On first pass, allocate space for angles
302	if (j == 0) {	528✔
303	auto n_mu = adist->x().size();	132✔
304	d.mu = tensor::Tensor<double>({d.n_e_out, n_mu});	264✔
305	}
306
307	// Copy outgoing angles
308	tensor::View<double> mu_j = d.mu.slice(j);	528✔
309	std::copy(adist->x().begin(), adist->x().end(), mu_j.begin());	528✔
310	}	528✔
311	}
312
313	distribution_.emplace_back(std::move(d));	132✔
314	}	132✔
315	}	44✔
316
317	void IncoherentInelasticAE::sample_params(	3,614,897✔
318	double E_in, double& E_out, double& f, int& l, int& j, uint64_t* seed) const
319	{
320	// Get index and interpolation factor for inelastic grid
321	int i;	3,614,897✔
322	double f0;	3,614,897✔
323	get_energy_index(energy_, E_in, i, f0);	3,614,897✔
324
325	// Pick closer energy based on interpolation factor
326	l = f0 > 0.5 ? i + 1 : i;	3,614,897✔
327
328	// Determine outgoing energy bin
329	// (First reset n_energy_out to the right value)
330	int n = distribution_[l].n_e_out;	3,614,897✔
331	double r1 = prn(seed);	3,614,897✔
332	double c_j = distribution_[l].e_out_cdf[0];	3,614,897✔
333	double c_j1;	3,614,897✔
334	for (j = 0; j < n - 1; ++j) {	8,721,537!
335	c_j1 = distribution_[l].e_out_cdf[j + 1];	8,721,537✔
336	if (r1 < c_j1)	8,721,537✔
337	break;
338	c_j = c_j1;	5,106,640✔
339	}
340
341	// check to make sure j is <= n_energy_out - 2
342	j = std::min(j, n - 2);	3,614,897!
343
344	// Get the data to interpolate between
345	double E_l_j = distribution_[l].e_out[j];	3,614,897!
346	double p_l_j = distribution_[l].e_out_pdf[j];	3,614,897✔
347
348	// Next part assumes linear-linear interpolation in standard
349	double E_l_j1 = distribution_[l].e_out[j + 1];	3,614,897✔
350	double p_l_j1 = distribution_[l].e_out_pdf[j + 1];	3,614,897✔
351
352	// Find secondary energy (variable E)
353	double frac = (p_l_j1 - p_l_j) / (E_l_j1 - E_l_j);	3,614,897✔
354	if (frac == 0.0) {	3,614,897!
355	E_out = E_l_j + (r1 - c_j) / p_l_j;	3,614,897✔
356	} else {
357	E_out = E_l_j +	×
358	(std::sqrt(std::max(0.0, p_l_j * p_l_j + 2.0 * frac * (r1 - c_j))) -	×
359	p_l_j) /	×
360	frac;
361	}
362
363	// Adjustment of outgoing energy
364	double E_l = energy_[l];	3,614,897✔
365	if (E_out < 0.5 * E_l) {	3,614,897✔
366	E_out = 2.0 E_in / E_l - 1.0;	344,476✔
367	} else {
368	E_out += E_in - E_l;	3,270,421✔
369	}
370
371	f = (r1 - c_j) / (c_j1 - c_j);	3,614,897✔
372	}	3,614,897✔
373	void IncoherentInelasticAE::sample(	3,614,897✔
374	double E_in, double& E_out, double& mu, uint64_t* seed) const
375	{
376	double f;	3,614,897✔
377	int l, j;	3,614,897✔
378	sample_params(E_in, E_out, f, l, j, seed);	3,614,897✔
379
380	// Sample outgoing cosine bin
381	int n_mu = distribution_[l].mu.shape(1);	3,614,897!
382	std::size_t k = prn(seed) * n_mu;	3,614,897✔
383
384	// Rather than use the sampled discrete mu directly, it is smeared over
385	// a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
386	// discrete mu value itself.
387	const auto& mu_l = distribution_[l].mu;	3,614,897✔
388
389	// Interpolate kth mu value between distributions at energies j and j+1
390	mu = mu_l(j, k) + f * (mu_l(j + 1, k) - mu_l(j, k));	3,614,897✔
391
392	// Inteprolate (k-1)th mu value between distributions at energies j and j+1.
393	// When k==0, pick a value that will smear the cosine out to a minimum of -1.
394	double mu_left =	3,614,897✔
395	(k == 0)
396	? mu_left = -1.0 - (mu + 1.0)	3,614,897✔
397	: mu_left = mu_l(j, k - 1) + f * (mu_l(j + 1, k - 1) - mu_l(j, k - 1));	3,159,464✔
398
399	// Inteprolate (k+1)th mu value between distributions at energies j and j+1.
400	// When k is the last discrete value, pick a value that will smear the cosine
401	// out to a maximum of 1.
402	double mu_right =	3,614,897✔
403	(k == n_mu - 1)	3,614,897✔
404	? mu_right = 1.0 + (1.0 - mu)	3,614,897✔
405	: mu_right = mu_l(j, k + 1) + f * (mu_l(j + 1, k + 1) - mu_l(j, k + 1));	3,160,762✔
406
407	// Smear cosine
408	mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);	5,427,510✔
409	}	3,614,897✔
410
NEW 411	double IncoherentInelasticAE::sample_energy_and_pdf(	×
412	double E_in, double mu, double& E_out, uint64_t* seed) const
413	{
NEW 414	double f;	×
NEW 415	int l, j;	×
NEW 416	sample_params(E_in, E_out, f, l, j, seed);	×
417
NEW 418	int n_mu = distribution_[l].mu.shape()[1];	×
NEW 419	const auto& mu_l = distribution_[l].mu;	×
420
NEW 421	double pdf = 0.0;	×
NEW 422	pdf += f * get_pdf_discrete(mu_l.slice(j + 1, tensor::all), mu);	×
NEW 423	pdf += (1 - f) * get_pdf_discrete(mu_l.slice(j, tensor::all), mu);	×
NEW 424	return pdf;	×
425	}
426
427	//==============================================================================
428	// MixedElasticAE implementation
429	//==============================================================================
430
431	MixedElasticAE::MixedElasticAE(	44✔
432	hid_t group, const CoherentElasticXS& coh_xs, const Function1D& incoh_xs)	44✔
433	: coherent_dist_(coh_xs), coherent_xs_(coh_xs), incoherent_xs_(incoh_xs)	44✔
434	{
435	// Read incoherent elastic distribution
436	hid_t incoherent_group = open_group(group, "incoherent");	44✔
437	std::string temp;	44✔
438	read_attribute(incoherent_group, "type", temp);	44✔
439	if (temp == "incoherent_elastic") {	44!
440	incoherent_dist_ = make_unique<IncoherentElasticAE>(incoherent_group);	×
441	} else if (temp == "incoherent_elastic_discrete") {	44!
442	auto xs = dynamic_cast<const Tabulated1D*>(&incoh_xs);	44✔
443	incoherent_dist_ =	44✔
444	make_unique<IncoherentElasticAEDiscrete>(incoherent_group, xs->x());	44✔
445	}
446	close_group(incoherent_group);	44✔
447	}	44✔
448
449	const AngleEnergy& MixedElasticAE::sample_dist(	46,486✔
450	double E_in, uint64_t* seed) const
451	{
452	// Evaluate coherent and incoherent elastic cross sections
453	double xs_coh = coherent_xs_(E_in);	46,486✔
454	double xs_incoh = incoherent_xs_(E_in);	46,486✔
455
456	if (prn(seed) * (xs_coh + xs_incoh) < xs_coh) {	46,486✔
457	return coherent_dist_;	45,144✔
458	} else {
459	return *incoherent_dist_;	1,342✔
460	}
461	}
462
463	void MixedElasticAE::sample(	46,486✔
464	double E_in, double& E_out, double& mu, uint64_t* seed) const
465	{
466	sample_dist(E_in, seed).sample(E_in, E_out, mu, seed);	46,486✔
467	}	46,486✔
468
NEW 469	double MixedElasticAE::sample_energy_and_pdf(	×
470	double E_in, double mu, double& E_out, uint64_t* seed) const
471	{
NEW 472	return sample_dist(E_in, seed).sample_energy_and_pdf(E_in, mu, E_out, seed);	×
473	}
474
475	} // namespace openmc

openmc-dev / openmc / 22593927413

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