Option to generate the same distribution sequence as sequential is important (for consistency)
SF F N A SA
9 3 2 0 0

Option to generate a distribution sequence different from sequential is important (for performance)
SF F N A SA
6 4 6 0 0

We must have an iterator based 'generate' interface
SF F N A SA
2 7 4 0 1

We must have a simd-type-producing interface
SF F N A SA
2 3 5 2 0 - Weak consensus

P1068R2 Vector API for random number generation (Ilya Burylov, Pavel Dyakov, Ruslan Arutyunyan, Andrey Nikolaev)

SG1 in Belfast.

We like the new algorithms for vectorized random number distributions, as a new
API that does not match the existing API's results, without consistency controls:
SF F N A SA
5 11 4 1 0
Consensus for this change

Forward to LEWG for target at LEWG's choosing:
SF F N A SA
No objection to unanimous consent

SG6 does not favor change; the original API doesn't promise repeatability, so saying the vector API is consistent with the existing API doesn't really mean anything.

P1068R3 Vector API for random number generation (Ilya Burylov, Pavel Dyakov, Ruslan Arutyunyan, Andrey Nikolaev)

Putting this on the LEWGI agenda as we're already seeing some random number papers and LEWG likely won't have time at this meeting for this.

Prague 2020-02 LEWGI Minutes

P1068R3 Make Random Number Generation Vectorizable: Design Review

Chair: Nevin Liber

Champion: Ilya Burylov

Minute Taker: Marco Foco

Start Review: 2020-02-11 14:50

Prior art: Yes, in paper.

This proposal changes the definition of the uniform_random_bit_generator; changing concepts is a breaking change. You probably need to add a new concept instead.

Regarding whether this provides enough implementation freedom, that's an SG1 or SG6 question. SG1 reviewed this and this is the amount of freedom they felt they needed.

Do we need 3 APIs:

• Scalar (what we have today).
• Vector and reproducible.
• Vector and not reproducible.

Clarify the design intent for random_device - should it have the vector API?

Start Polling: 15:26

POLL: Ask SG1 to consider the capability of a vector URBG that is unconstrained in reproducing the scalar results (the goal being as much performance as possible).

Attendance: 22

# of Authors: 1

Author Position: SA

That has no consensus.

End: 15:34

CONSENSUS: LEWGI sends P1068R3 (Make Random Number Generation Vectorizable), with the guidance below, to LEWG.

• Instead of changing uniform_random_bit_generator, introduce a new concept that subsumes it.

P1068R4 Vector API for random number generation (Ilya Burylov, Pavel Dyakov, Ruslan Arutyunyan, Andrey Nikolaev)

P1068R8 Vector API for random number generation (Ilya Burylov, Pavel Dyakov, Ruslan Arutyunyan, Andrey Nikolaev, Alina Elizarova)

P1068R9 was added to LEWG 2023 September electronic poll paper (P2972R0)

P1068R9 was forwarded to LWG on LEWG 2023 September electronic poll (P3020R0)

2023-11-28 Library Evolution Telecon

P1068R9: Vector API for random number generation

2023-11-28 Library Evolution Telecon Minutes

Champion: Ruslan Arutyunyan

Chair: Ben Craig

Minute Taker: Mark Hoemmen

Summary

LWG wants changing the std::ranges::generate_random customization point to find a generate_random member function of generator and distribution rather than finding one by ADL (status QUO of the paper). The problem is LEWG explicitly voted that generate_random should not be a member function. Although, it’s not quite the same question because we still provide std::ranges::generate_random as the CPO (as LEWG requested) we want to make sure we don’t violate the design intent.

POLL: Change generate_random customization point to find a generate_random member function, rather than use ADL (i.e. change the paper to do what LWG wants)

Attendance: 14

# of Authors: 2

Author Position: N, WF

Outcome: Consensus in favor

WA: because it prevents a third party from optimizing a generator for vectorization

Next Steps

LEWG approved the recommended change. The paper will go back to LWG to continue the wording review.

P1068R10 Vector API for random number generation (Ilya Burylov, Pavel Dyakov, Ruslan Arutyunyan, Andrey Nikolaev, Alina Elizarova)

P1068R11 Vector API for random number generation (Ilya Burylov, Pavel Dyakov, Ruslan Arutyunyan, Andrey Nikolaev, Alina Elizarova)