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Move distributions into random_dist.h/cpp

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Paul Romano 2021-04-26 10:00:21 -05:00
parent 516745ce87
commit f0aaac4601
9 changed files with 131 additions and 114 deletions
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67
include/openmc/math_functions.h
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@ -8,9 +8,7 @@
#include <complex>
#include <cstdlib>
#include "openmc/constants.h"
#include "openmc/position.h"
#include "openmc/random_lcg.h"
namespace openmc {
@ -138,71 +136,6 @@ extern "C" void rotate_angle_c(double uvw[3], double mu, const double* phi,
Direction rotate_angle(Direction u, double mu, const double* phi,
uint64_t* seed);
//==============================================================================
//! Samples an energy from the Maxwell fission distribution based on a direct
//! sampling scheme.
//!
//! The probability distribution function for a Maxwellian is given as
//! p(x) = 2/(T*sqrt(pi))*sqrt(x/T)*exp(-x/T). This PDF can be sampled using
//! rule C64 in the Monte Carlo Sampler LA-9721-MS.
//!
//! \param T The tabulated function of the incoming energy
//! \param seed A pointer to the pseudorandom seed
//! \return The sampled outgoing energy
//==============================================================================
extern "C" double maxwell_spectrum(double T, uint64_t* seed);
//==============================================================================
//! Samples an energy from a Watt energy-dependent fission distribution.
//!
//! Although fitted parameters exist for many nuclides, generally the
//! continuous tabular distributions (LAW 4) should be used in lieu of the Watt
//! spectrum. This direct sampling scheme is an unpublished scheme based on the
//! original Watt spectrum derivation (See F. Brown's MC lectures).
//!
//! \param a Watt parameter a
//! \param b Watt parameter b
//! \param seed A pointer to the pseudorandom seed
//! \return The sampled outgoing energy
//==============================================================================
extern "C" double watt_spectrum(double a, double b, uint64_t* seed);
//==============================================================================
//! Samples an energy from the Gaussian energy-dependent fission distribution.
//!
//! Samples from a Normal distribution with a given mean and standard deviation
//! The PDF is defined as s(x) = (1/2*sigma*sqrt(2) * e-((mu-x)/2*sigma)^2
//! Its sampled according to
//! http://www-pdg.lbl.gov/2009/reviews/rpp2009-rev-monte-carlo-techniques.pdf
//! section 33.4.4
//!
//! @param mean mean of the Gaussian distribution
//! @param std_dev standard deviation of the Gaussian distribution
//! @param seed A pointer to the pseudorandom seed
//! @result The sampled outgoing energy
//==============================================================================
extern "C" double normal_variate(double mean, double std_dev, uint64_t* seed);
//==============================================================================
//! Samples an energy from the Muir (Gaussian) energy-dependent distribution.
//!
//! This is another form of the Gaussian distribution but with more easily
//! modifiable parameters
//! https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-05411-MS
//!
//! @param e0 peak neutron energy [eV]
//! @param m_rat ratio of the fusion reactants to AMU
//! @param kt the ion temperature of the reactants [eV]
//! @param seed A pointer to the pseudorandom seed
//! @result The sampled outgoing energy
//==============================================================================
extern "C" double muir_spectrum(double e0, double m_rat, double kt,
uint64_t* seed);
//==============================================================================
//! Constructs a natural cubic spline.
//!

74
include/openmc/random_dist.h Normal file
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@ -0,0 +1,74 @@
#ifndef OPENMC_RANDOM_DIST_H
#define OPENMC_RANDOM_DIST_H
#include <cstdint> // for uint64_t
namespace openmc {
//==============================================================================
//! Samples an energy from the Maxwell fission distribution based on a direct
//! sampling scheme.
//!
//! The probability distribution function for a Maxwellian is given as
//! p(x) = 2/(T*sqrt(pi))*sqrt(x/T)*exp(-x/T). This PDF can be sampled using
//! rule C64 in the Monte Carlo Sampler LA-9721-MS.
//!
//! \param T The tabulated function of the incoming energy
//! \param seed A pointer to the pseudorandom seed
//! \return The sampled outgoing energy
//==============================================================================
extern "C" double maxwell_spectrum(double T, uint64_t* seed);
//==============================================================================
//! Samples an energy from a Watt energy-dependent fission distribution.
//!
//! Although fitted parameters exist for many nuclides, generally the
//! continuous tabular distributions (LAW 4) should be used in lieu of the Watt
//! spectrum. This direct sampling scheme is an unpublished scheme based on the
//! original Watt spectrum derivation (See F. Brown's MC lectures).
//!
//! \param a Watt parameter a
//! \param b Watt parameter b
//! \param seed A pointer to the pseudorandom seed
//! \return The sampled outgoing energy
//==============================================================================
extern "C" double watt_spectrum(double a, double b, uint64_t* seed);
//==============================================================================
//! Samples an energy from the Gaussian energy-dependent fission distribution.
//!
//! Samples from a Normal distribution with a given mean and standard deviation
//! The PDF is defined as s(x) = (1/2*sigma*sqrt(2) * e-((mu-x)/2*sigma)^2
//! Its sampled according to
//! http://www-pdg.lbl.gov/2009/reviews/rpp2009-rev-monte-carlo-techniques.pdf
//! section 33.4.4
//!
//! \param mean mean of the Gaussian distribution
//! \param std_dev standard deviation of the Gaussian distribution
//! \param seed A pointer to the pseudorandom seed
//! \result The sampled outgoing energy
//==============================================================================
extern "C" double normal_variate(double mean, double std_dev, uint64_t* seed);
//==============================================================================
//! Samples an energy from the Muir (Gaussian) energy-dependent distribution.
//!
//! This is another form of the Gaussian distribution but with more easily
//! modifiable parameters
//! https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-05411-MS
//!
//! \param e0 peak neutron energy [eV]
//! \param m_rat ratio of the fusion reactants to AMU
//! \param kt the ion temperature of the reactants [eV]
//! \param seed A pointer to the pseudorandom seed
//! \result The sampled outgoing energy
//==============================================================================
extern "C" double muir_spectrum(double e0, double m_rat, double kt, uint64_t* seed);
} // namespace openmc
#endif // OPENMC_RANDOM_DIST_H