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moved alias method to function and fixed sampling bug

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This commit is contained in:
myerspat 2022-12-19 17:24:33 -05:00
parent 907cf7df4d
commit 90509d928b
2 changed files with 14 additions and 5 deletions
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3
include/openmc/distribution.h
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@ -58,6 +58,9 @@ private:
//! Normalize distribution so that probabilities sum to unity
void normalize();
//! Initialize alias tables for distribution
void init_alias();
};
//==============================================================================

16
src/distribution.cpp
View file

@ -29,12 +29,18 @@ Discrete::Discrete(pugi::xml_node node)
std::copy(params.begin(), params.begin() + n / 2, std::back_inserter(x_));
std::copy(params.begin() + n / 2, params.end(), std::back_inserter(p_));
normalize();
// Initialize alias tables
init_alias();
}
Discrete::Discrete(const double* x, const double* p, int n)
: x_ {x, x + n}, p_ {p, p + n}
{
// Initialize alias tables
init_alias();
}
void Discrete::init_alias() {
normalize();
// Vectors for large and small probabilities based on 1/n
@ -42,11 +48,11 @@ Discrete::Discrete(const double* x, const double* p, int n)
vector<size_t> small;
// Set and allocate memory
alias_.reserve(n);
alias_.reserve(x_.size());
// Fill large and small vectors based on 1/n
for (int i = 0; i < n; i++) {
p_[i] *= n;
for (int i = 0; i < x_.size(); i++) {
p_[i] *= x_.size();
if (p_[i] > 1.0) {
large.push_back(i);
} else {
@ -85,7 +91,7 @@ double Discrete::sample(uint64_t* seed) const
return x_[alias_[u]];
}
} else {
return x_.size();
return x_[0];
}
}