leapfrog

oneMKL - Data Parallel C++ Developer Reference

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ID 772045

Date 3/22/2024

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leapfrog

Proceed state of engine using the leapfrog method.

Description
API

Description

The leapfrog function generates random numbers in an engine with non-unit stride. This feature is particularly useful in distributing random numbers from the original stream across the stride buffers without generating the original random sequence with subsequent manual distribution.

One of the important applications of the leapfrog method is splitting the original sequence into non-overlapping subsequences across stride computational nodes. The function initializes the original random stream (see the following figure) to generate random numbers for the computational node idx, 0 ≤ idx < stride, where stride is the largest number of computational nodes used.

Leapfrog Method

Leapfrog Method

The leapfrog method is supported only for those basic generators that allow splitting elements by the leapfrog method, which is more efficient than simply generating them by a generator with subsequent manual distribution across computational nodes. See VS Notes for details.

The following code illustrates the initialization of three independent streams using the leapfrog method:

Code for Leapfrog Method

   // Creating 3 identical engines
   mkl::rng::mcg31m1 engine_1(queue, seed);


   mkl::rng::mcg31m1 engine_2(engine_1);
   mkl::rng::mcg31m1 engine_3(engine_1);


   // Leapfrogging the states of engines
   mkl::rng::leapfrog(engine_1, 0 , 3);
   mkl::rng::leapfrog(engine_2, 1 , 3);
   mkl::rng::leapfrog(engine_3, 2 , 3);
   // Generating random numbers
   ...

API

Syntax

namespace oneapi::mkl::rng {
  template<typename Engine>
  void leapfrog (Engine& engine,
                 std::uint64_t idx,
                 std::uint64_t stride)
}

Include Files

oneapi/mkl/rng.hpp

Input Parameters

Name	Type	Description
engine	`Engine`	Object of engine class, which supports leapfrog.
idx	`std::uint64_t`	Index of the computational node.
stride	`std::uint64_t`	Largest number of computational nodes, or stride.

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leapfrog

Description

API