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Subject: Re: [SG14] [EXTERNAL] Re: Linear Algebra SIG Call - February 6, 2019
From: Hoemmen, Mark (mhoemme_at_[hidden])
Date: 2019-02-06 13:01:15


Hi Bob! Thanks for the meeting prep! I won't be able to call in, but I have a few comments:

P1166R0:

PLEASE PLEASE DON'T OVERLOAD COMMA PLEASE (this makes a lot of parameter pack code harder to write -- I'm hoping that the language ultimately gets rid of the ability to overload operator comma -- in fact, San Diego had at least one proposal that would restrict where overloaded operator comma is allowed to work). Can we get some of this effect via clever std::initializer_list?

Re. overloading arithmetic operators:
  - If it could create a temporary, it shouldn't be overloaded (e.g., matrix-matrix multiply).
  - Users will want a function call option that doesn't create a temporary anyway.
 
In the 2000's, LAPACK switched from Fortran 77 to a subset of Fortran 90. Developers polled users whether the interface should be allowed to allocate scratch space internally. Users rejected this, because it would hinder use in embedded environments. This suggests that some users will always want access to a low-level interface that can promise that it won't allocate.

mfh

On 2/6/19, 10:46 AM, "SG14 on behalf of Bob Steagall" <sg14-bounces_at_[hidden] on behalf of bob.steagall.cpp_at_[hidden]> wrote:

    All,
    
    Here is a tentative agenda for today's call:
    
    1. I'd like to first see if there are any new thoughts regarding
    P1166R0 since the last call.
    
    2. P1416R0 lays out some linear algebra requirements from the
    perspective of SG19; if someone will be on the call to present this
    paper, that would be much appreciated.
    
    3. If there is interest in revisiting P1417, the historical lessons
    paper, we can discuss that. Mark Hoemmen won't be on the call today,
    though, so we may need another co-author to lead.
    
    4. I'd like to then discuss P1385, the API design proposal by Guy and
    myself. The R0 version was in the pre-Kona mailing, but there is now
    an R1-draft version that corrects some mistakes and adds a little more
    material.
    
    For reference, I've attached P1166R0, P1385R0, P1385R1-draft, P1416R0,
    and P1417R0.
    
    Thanks,
    --Bob
    
    
    On Tue, Feb 5, 2019 at 1:21 PM Bob Steagall <bob.steagall.cpp_at_[hidden]> wrote:
>
> Bob Steagall is inviting you to a scheduled Zoom meeting.
>
> Topic: SG14 Linear Algebra SIG Call - February 2019
> Time: Feb 6, 2019 3:00 PM Eastern Time (US and Canada)
>
> Join Zoom Meeting
> https://zoom.us/j/666350568
>
> One tap mobile
> +16465588656,,666350568# US (New York)
> +17207072699,,666350568# US
>
> Dial by your location
> +1 646 558 8656 US (New York)
> +1 720 707 2699 US
> Meeting ID: 666 350 568
> Find your local number: https://zoom.us/u/abxFIgIaPQ
>
> I don't yet have a specific agenda, although I though we might look at P1385.
>
> Please e-mail me any suggestions for papers/topics to discuss.
>
> Thanks,
> --Bob
    


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