Unyt

------------------

* Fix a future incompatibility with numpy 1.25 (unreleased) where comparing
``unyt_array`` objects to non-numeric objects (e.g. strings) would cause a
crash. See `PR 333 <https://github.com/yt-project/unyt/pull/333>`_. Thank you
to Clément Robert (neutrinoceros on GitHub) and Nathan Goldbaum (ngoldbaum
on GitHub) for the contribution.

------------------

* Fix an issue where taking powers of units was backwards-incompatible with previous
versions of ``unyt`` when the exponent is not zero. See `PR 249
<https://github.com/yt-project/unyt/pull/249>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.
* The import time for ``unyt`` has been reduced by skipping version checking of
other packages. See `PR 251
<https://github.com/yt-project/unyt/pull/251>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.

------------------

* Dropped support for Python 3.6 and 3.7.
* Added support for Python 3.8, 3.9 and 3.10.
* Fix an issue where SI prefixes of the ``degC`` units would give incorrect
values in conversions. See `PR 176
<https://github.com/yt-project/unyt/pull/176>`_. Thank you to Lee Johnston
(l-johnston on GitHub) for the contribution.
* Fix an issue when using ``matplotlib_support``, plot an empty unyt array,
would result in an error when changing units. See `PR 180
<https://github.com/yt-project/unyt/pull/180>`_. Thank you to Josh Borrow
(JBorrow on GitHub) for the contribution.
* Fix an issue where units would be printed twice in formatted strings with
an ``unyt_array`` embedded. See `PR 188
<https://github.com/yt-project/unyt/pull/188>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.
* Add a method to parse a ``unyt_quantity`` from a string expression. See `PR 191
<https://github.com/yt-project/unyt/pull/191>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.
* Fix an issue where a ``unyt_array`` with dtype int8 could not be converted
to a different unit. See `PR 197
<https://github.com/yt-project/unyt/pull/197>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.
* The import time for ``unyt`` has been reduced. See `PR 199
<https://github.com/yt-project/unyt/pull/199>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.
* Fix an issue where taking an ``unyt_array`` or ``unyt_quantity`` to a zero
power would retain the units of the original array or quantity instead of
converting to a dimensionless array. See `PR 204
<https://github.com/yt-project/unyt/pull/204>`_. Thank you to Josh Borrow
(JBorrow on GitHub) for the contribution.
* Add support for coercing iterables of ``unyt_array`` objects with nonuniform
dimensionally equivalent units to a single ``unyt_array``. See `PR 211
<https://github.com/yt-project/unyt/pull/211>`_. Thank you to Nathan Goldbaum
(ngoldbaum on GitHub) for the contribution.
* Add the civil engineering units ``pli``, ``plf``, ``psf``, ``kli``, ``klf``,
and ``ksf``. See `PR 217 <https://github.com/yt-project/unyt/pull/217>`_.
Thank you to osnippet on GitHub for the contribution.
* Fix typos in constants and unit prefixes. See `PR 218
<https://github.com/yt-project/unyt/pull/218>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the contribution.
* Fix an issue where multiplying a 1-element ``unyt_array`` would return a
``unyt_quantity``. See `PR 225 <https://github.com/yt-project/unyt/pull/225>`_.
Thank you to Clément Robert (neutrinoceros on GitHub) for the contribution.
* Add the Rydberg constant ``R_∞`` and unit ``Ry``, add the dimension
``angular_frequency`` and the unit ``rpm``, and increase the precision of
Avogadro's number. See `PR 228 <https://github.com/yt-project/unyt/pull/228>`_.
* Fix an issue where ``np.divide.reduce`` would return incorrect units for ``unyt_array``
instances. See `PR 230 <https://github.com/yt-project/unyt/pull/230>`_.
Thank you to Kyle Oman (kyleaoman on GitHub) for the contribution.

------------------

* Dropped support for Python 3.5.
* Add ``delta_degC`` and ``delta_degF`` units to support temperature difference
arithmetic. See `PR 152
<https://github.com/yt-project/unyt/pull/152>`_. Thank you to Lee Johnston
(l-johnston on GitHub) for the contribution.
* Fix an issue where a subsequent load of the unit registry with units that are
equal but not identical leads to a crash. See `PR 158
<https://github.com/yt-project/unyt/pull/158>`_. Thank you to Matthew Turk
(matthewturk on GitHub) for the initial bug report and fix.
* Add force unit ``kip`` and pressure unit ``psi``. Thank you to P. Talley
(otaithleigh on GitHub) for the contribution. See `PR 162
<https://github.com/yt-project/unyt/pull/162>`_.
* Fix an issue where arithmetic operations on units defined in different
registries and having the conversion defined in one direction would lead to a
crash. See `PR 164 <https://github.com/yt-project/unyt/pull/164>`_. Thank
you to Clément Robert (neutrinoceros on GitHub) for the initial bug report
and fix.

------------------

* The ``unyt.returns`` and ``unyt.accepts`` decorators now work correctly for
functions that accept or return data with dimensionless units. See `PR 146
<https://github.com/yt-project/unyt/pull/146>`_. Thank you to Simon Schopferer
(simfinite on GitHub) for the initial bug report and fix.
* Data used in the tests are packaged with the source distribution and
``unyt.test()`` is now itself run as part of unyt's continuous integration
tests. See `PR 149 <https://github.com/yt-project/unyt/pull/149>`_ and `PR
150 <https://github.com/yt-project/unyt/pull/150>`_. Thank you to Miguel de
Val-Borro (migueldvb on GitHub) for the initial bug report and fix.
* The ``degC`` and ``degF`` units now render as ``°C`` and ``°F`` by default,
``°C`` and ``°F`` are now recognized as valid unit names as well. Thank you to
Lee Johnston (l-johnston on GitHub) for the contribution.
* Use a more canonical representation of the micro symbol when printing units
with the micro prefix, avoiding issues with displaying unit names in
Matplotlib plot labels. See `PR 153
<https://github.com/yt-project/unyt/pull/153>`_. Thank you to Matthew Turk
(matthewturk on GitHub) for the bug report and fix.
* Add more alternative spellings for solar units. See `PR 155
<https://github.com/yt-project/unyt/pull/155>`_. Thank you to Clément Robert
(neutrinoceros on GitHub) for the initial bug report.

------------------

* Fix compatibility with ``unyt_array`` subclasses that do not have the new
``name`` argument in their initializer. See `PR 140
<https://github.com/yt-project/unyt/pull/140>`_.
* Fix an issue where custom units added to a unit registry were not restored
correctly when reloading a unit registry from a JSON or pickle
representation. See `PR 140 <https://github.com/yt-project/unyt/pull/140>`_.