celeritas::Selector< F, T > Class Template Reference

On-the-fly selection of a weighted discrete distribution. More...

#include <Selector.hh>

Public Types
Type aliases
using	value_type = T
using	real_type = typename std::invoke_result< F, value_type >::type

Public Member Functions
CELER_FUNCTION	Selector (F &&eval, value_type size, real_type total)
	Construct with function, size, and accumulated value.
template<class Engine >
CELER_FUNCTION T	operator() (Engine &rng) const
	Sample from the distribution.

Detailed Description

template<class F, class T>
class celeritas::Selector< F, T >

On-the-fly selection of a weighted discrete distribution.

This algorithm encapsulates the loop for sampling from distributions by integer index or by OpaqueId. Edge cases are thoroughly tested (it will never iterate off the end, even for incorrect values of the "total" probability/xs), and it uses one fewer register than the typical accumulation algorithm. When building with debug checking, the constructor asserts that the provided "total" value is consistent.

The given function must return a consistent value for the same given argument.

auto select_el = make_selector(
    [](ElementId i) { return xs[i.get()]; },
    ElementId{num_elements()},
    tot_xs);
ElementId el = select_el(rng);

or

auto select_val = make_selector([](size_type i) { return pdf[i]; },
                                pdf.size());
size_type idx = select_val(rng);

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The documentation for this class was generated from the following file:

• Selector.hh