[yt-dev] Re: Incorrect vector components in curvilinear coordinate systems

8 Feb 2018

      What do you think of addressing this problem together with the bulk 
field parameter issue (https://github.com/yt-project/yt/issues/1686)?

Otherwise some fields (such as the velocity field) might yield 
inconsistent results (Cartesian magnitude != magnitude based on a 
spherical decomposition) for datasets with the bulk field parameter set.
If it is decided not to be fixed and backported now, I would at least 
argue to update the documentation and add a line to the release notes 
about the (underlying/implicit) differences.

Philipp

On 02/08/2018 04:03 PM, Cameron Hummels wrote:
...
Agreed.  Thanks, everyone!
On Thu, Feb 8, 2018 at 1:01 PM, John Zuhone mailto:jzuhone@gmail.com> wrote:
I think this is fine, so long as we say something at the top like
    “this release has some important bugfixes”.
...
On Feb 8, 2018, at 3:57 PM, Nathan Goldbaum mailto:nathan12343@gmail.com> wrote:
Maybe the thing to do is merge my PR, backport it to stable, do a
    bugfix release, and make a big deal about this issue in the
    release notes.
We're overdue for a bugfix release anyway and doing a release will
    make it easier for our users to get the fix, rather than applying
    it themselves or installing yt from source.
-Nathan
On Thu, Feb 8, 2018 at 2:25 PM, John Zuhone mailto:jzuhone@gmail.com> wrote:
I suspect that any user who is doing analysis right now using
        these fields might want to know right now about this bug so
        that they can apply the fix immediately if they so desire
        before they publish something on them.
In fact, my student is working on a project using these very
        fields and I just told him that we’ll need to do that very
        thing—apply this fix and he’ll have to re-run stuff (not a big
        deal).
So for that reason we should email yt-users. It’s embarrassing
        but let’s be honest—we’re not perfect, and even if some people
        are cranky with us I think that it’s good practice to be very
        open about these things because I think our users would
        appreciate it.
...
On Feb 8, 2018, at 3:09 PM, Nathan Goldbaum
        mailto:nathan12343@gmail.com> wrote:
Hi all,
I'd like to point out a pull request I just made, which fixes
        a number of fields that have been returning incorrect data.
        In particular, the definitions of the fields
        `velocity_spherical_theta`, `velocity_spherical_phi`, and
        `velocity_cylindrical_theta` have not been correct for at
        least three years, possibly longer - I haven't checked to see
        if they were ever correct.
Here's a pull request that implements a fix and adds some new
        tests:
https://github.com/yt-project/yt/pull/1687
        https://github.com/yt-project/yt/pull/1687
While it's nice that we know there's an issue now and that
        it's fixed, this means that if someone was making a profile
        of the tangential velocity around a star, or the poloidal
        magnetic field in a disk simulation, or a circular velocity
        in a galaxy simulation, yt may have silently returned
        incorrect results.
I'm raising this issue here because it feels like it might be
        a big deal. Should this concern be raised more loudly to our
        users? I'm hesitant to do so, mostly out of sheepishness. Is
        this as big a deal as I'm making it out to be?
Thanks,
Nathan
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-- 
Cameron Hummels
NSF Postdoctoral Fellow
Department of Astronomy
California Institute of Technology
http://chummels.org
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[yt-dev] Re: Incorrect vector components in curvilinear coordinate systems

Philipp Grete