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Const-seed rng #366

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Merged
JamesMcClung merged 2 commits into from
Nov 21, 2025
Merged

Const-seed rng #366

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00b8e87
rng: rename GeneratorPtr
JamesMcClung Nov 3, 2025
680d0a6
rng: +constant generator support
JamesMcClung Nov 3, 2025
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25 changes: 20 additions & 5 deletions src/include/rng.hxx
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Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,8 @@ namespace rng
namespace detail
{
using Generator = std::default_random_engine;
using ProcessGeneratorPtr = std::shared_ptr<Generator>;
ProcessGeneratorPtr process_generator;
using GeneratorPtr = std::shared_ptr<Generator>;
GeneratorPtr process_generator;

int get_process_seed()
{
Expand All @@ -25,14 +25,20 @@ int get_process_seed()
return 10000 * (rank + 1);
}

ProcessGeneratorPtr get_process_generator()
GeneratorPtr get_process_generator()
{
if (!process_generator) {
process_generator = std::make_shared<Generator>(get_process_seed());
}
return process_generator;
}

GeneratorPtr get_constant_generator(int seed)
{
// FIXME this doesn't need to be a shared pointer
return std::make_shared<Generator>(seed);
}

} // namespace detail

// ======================================================================
Expand All @@ -41,6 +47,10 @@ ProcessGeneratorPtr get_process_generator()
template <typename Real>
struct Uniform
{
Uniform(Real min, Real max, int seed)
: dist(min, max), gen(detail::get_constant_generator(seed))
{}

Uniform(Real min, Real max)
: dist(min, max), gen(detail::get_process_generator())
{}
Expand All @@ -50,7 +60,7 @@ struct Uniform
Real get() { return dist(*gen); }

private:
detail::ProcessGeneratorPtr gen;
detail::GeneratorPtr gen;
std::uniform_real_distribution<Real> dist;
};

Expand All @@ -60,9 +70,14 @@ private:
template <typename Real>
struct Normal
{
Normal(Real mean, Real stdev, int seed)
: dist(mean, stdev), gen(detail::get_constant_generator(seed))
{}

Normal(Real mean, Real stdev)
: dist(mean, stdev), gen(detail::get_process_generator())
{}

Normal() : Normal(0, 1) {}

Real get() { return dist(*gen); }
Expand All @@ -74,7 +89,7 @@ struct Normal
}

private:
detail::ProcessGeneratorPtr gen;
detail::GeneratorPtr gen;
std::normal_distribution<Real> dist;
};

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