Notes:
Statistical Library Design Discussion
Overview

The meeting reviewed statistical library design updates and focused on how
users should control result types for statistical functions.
Design Decisions

   - Clarified standard deviation as the square root of the absolute
   variance and corrected range terminology for parallel implementations.
   - Tightened statistical definitions to prevent division by zero.
   - Preferred named structures, including statistical_set-style types and
   named mean/standard-deviation results, over Boolean flags or positional
   values.
   - Special values will not currently be checked; the treatment of silent
   NaNs and other constraints remains unresolved.

Type Promotion

   - Automatic promotion, user-side data transformation, and initialization
   parameters were viewed as poor approaches because they can be surprising,
   costly, or mathematically unsuitable.
   - The preferred design is an explicit return-type template argument; the
   group suggested requiring it for every call rather than providing an
   overload with an implicit default.

Open Questions

   - Should the API require users to specify the internal and return type
   on every call?
   - How will the design behave in real codebases, and what usage patterns
   will emerge from repository-based examples?

Action Items

   - Update the Croydon-related values in the paper to reflect the
   committee's vote.
   - Change the statistical functions to require an explicitly specified
   return type rather than supporting the overload that infers it.
   - Search GitHub repositories for programs that compute statistics and
   identify candidate codebases to update with ranges and the proposed
   statistical API, then use them to evaluate the interface.

Outline Standards Updates

   - Standard deviation uses the square root of the absolute variance.
   - Parallel implementations use forward ranges.
   - Statistical definitions were revised to avoid division by zero.

API Naming

   - Statistical sample and population options are represented as
   structures rather than Boolean parameters.
   - Named structures are favored for paired results such as mean and
   standard deviation.

Special Values

   - The current direction is not to check for special values.
   - Silent NaNs and additional constraints requiring branching remain
   under consideration.

Return-Type Promotion

   - Discussed four approaches: no transformation, automatic promotion, an
   initialization parameter, and an explicit return-type template argument.
   - The explicit return-type approach was favored, with discussion about
   requiring it on every call.

Implementation Evidence

   - The discussion emphasized the need to examine real programs that
   compute statistics and use ranges, rather than relying only on library
   publication examples.





On Thu, Oct 8, 2026 at 2:02 PM Michael Wong <fraggamuffin_at_[hidden]> wrote:

> Sorry this is the wrong callin zoom. Please use this:
> https://iso.zoom.us/j/92872076567?pwd=vftBSI36jdDvpehrxaY3Rs5un5pgk8.1
>
> On Thu, Oct 8, 2026 at 10:05 AM Michael Wong <fraggamuffin_at_[hidden]>
> wrote:
>
>> Topic: SG19 Machine Learning Monthly Meeting
>> Focus: Stats
>> Time: 02:00 PM Eastern Time (US and Canada)
>> Every month on the Second Thu
>>
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>>
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>> 1. Opening and introduction
>>
>> *ISO Code of Conduct:*
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>>
>> -
>>
>> *1.1* Roll call of participants
>>
>>
Michael Wong (CA)
Pete Isensee
Richard Dosselmann
Samuel Obeng
Vinnie Falco
>
>
>> -
>>
>> *1.2* Adopt agenda
>> -
>>
>> *1.3* Action items from previous meetings
>> -
>>
>> 1.4 Approve previous meeting minutes.
>>
>> 2. Main issues (125 min)
>>
>> *2.1 General logistics*
>>
>> -
>>
>> Future and past meeting plans (see section
>>
>> *2.2 Any proposal for reviews?*
>>
>> * Graph is scheduled for this month.*
>>
>> -
>>
>> SG14/SG19 features/issues/defects:
>>
>>
>> https://docs.google.com/spreadsheets/d/1JnUJBO72QVURttkKr7gn0_WjP--P0vAne8JBfzbRiy0/edit#gid=0
>>
>> *2.3 Domain-specific discussions*
>>
>> *2.4 Other Papers and proposals*
>>
>> *2.5 Future F2F meetings:*
>>
>> *2.6 Future C++ Standard meetings:*
>>
>> https://isocpp.org/std/meetings-and-participation/upcoming-meetings
>> 3. Any other business
>>
>> 4. Review
>>
>> 4.1 Review and approve resolutions and issues [e.g., changes to SG's
>> working draft]
>>
>> 4.2 Review action items (5 min)
>>
>> 5. Closing process
>>
>> 5.1 Establish next agenda
>>
>>
>> 5.2 Future meeting
>> Jan 15, 2026 02:00 PM ET: Statistics DONE
>> Feb 12, 2026 02:00 PM ET: Graph DONE
>> Mar 12, 2026 02:00 PM ET: Statistics; F2F London Cancelled
>> Apr 9, 2026 02:00 PM ET: Graph DONE
>> May 14, 2026 02:00 PM ET: Statistics Cancelled
>> June 11, 2026 02:00 PM ET: F2F cancelled
>> July 9, 2026 02:00 PM ET: Graph
>> Aug 13, 2026 06:00 PM ET: Statistics Cancelled
>> Sep 10, 2026 02:00 PM ET: CPPCON 9/12-18 Live call
>> Oct 8, 2026 02:00 PM ET: Stats
>> Nov 12, 2026 02:00 PM ET: F2F, cancelled
>> Dec 10, 2026 02:00 PM ET: Graph
>>
>