Empymod

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

**2018-05-21**

These changes should make calculations using ``QWE`` and ``QUAD`` for the
Hankel transform for cases which do not require all kernels faster; sometimes
as much as twice as fast. However, it might make calculations which do require
all kernels a tad slower, as more checks had to be included. (Related to
[`empymod11 <https://github.com/emsig/empymod/issues/11>`_]; basically
including for ``QWE`` and ``QUAD`` what was included for ``DLF`` in version
1.6.0.)

- ``transform``:

- ``dlf``:

- Improved by avoiding unnecessary multiplications/summations for empty
kernels and applying the angle factor only if it is not 1.
- Empty/unused kernels can now be input as ``None``, e.g. ``signal=(PJ0,
None, None)``.
- ``factAng`` is new optional for the Hankel transform, as is ``ab``.

- ``hqwe``: Avoids unnecessary calculations for zero kernels, improving speed
for these cases.

- ``hquad``, ``quad``: Avoids unnecessary calculations for zero kernels,
improving speed for these cases.

- ``kernel``:

- Simplify ``wavenumber``
- Simplify ``angle_factor``

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

**2018-05-05**

Secondary field calculation.

- Add the possibility to calculate secondary fields only (excluding the direct
field) by passing the argument ``xdirect=None``. The complete
``xdirect``-signature is now (only affects calculation if src and rec are in
the same layer):

- If True, direct field is calculated analytically in the frequency domain.
- If False, direct field is calculated in the wavenumber domain.
- If None, direct field is excluded from the calculation, and only reflected
fields are returned (secondary field).

- Bugfix in ``model.analytical`` for ``ab=[36, 63]`` (zeroes)
[`empymod16 <https://github.com/emsig/empymod/issues/16>`_].

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

**2018-05-01**

This release is not completely backwards compatible for the main modelling
routines in ``empymod.model``, but almost. Read below to see which functions
are affected.

- Improved Hankel DLF
[`empymod11 <https://github.com/emsig/empymod/issues/11>`_].
``empymod.kernel.wavenumber`` always returns three kernels, ``PJ0``, ``PJ1``,
and ``PJ0b``. The first one is angle-independent, the latter two depend on
the angle. Now, depending of what source-receiver configuration is chosen,
some of these might be zero. If-statements were now included to avoid the
calculation of the DLF, interpolation, and reshaping for 0-kernels, which
improves speed for these cases.

- Unified DLF arguments
[`empymod10 <https://github.com/emsig/empymod/issues/10>`_].

These changes are backwards compatible for all main modelling routines in
``empymod.model``. However, they are not backwards compatible for the
following routines:

- ``empymod.model.fem`` (removed ``use_spline``),
- ``empymod.transform.fht`` (removed ``use_spline``),
- ``empymod.transform.hqwe`` (removed ``use_spline``),
- ``empymod.transform.quad`` (removed ``use_spline``),
- ``empymod.transform.dlf`` (``lagged``, ``splined`` => ``pts_per_dec``),
- ``empymod.utils.check_opt`` (no longer returns ``use_spline``),
- ``empymod.utils.check_hankel`` (changes in ``pts_per_dec``), and
- ``empymod.utils.check_time`` (changes in ``pts_per_dec``).

The function ``empymod.utils.spline_backwards_hankel`` can be used for
backwards compatibility.

Now the Hankel and Fourier DLF have the same behaviour for ``pts_per_dec``:

- ``pts_per_dec = 0``: Standard DLF,
- ``pts_per_dec < 0``: Lagged Convolution DLF, and
- ``pts_per_dec > 0``: Splined DLF.

**There is one exception** which is not backwards compatible: Before, if
``opt=None`` and ``htarg={pts_per_dec: != 0}``, the ``pts_per_dec`` was not
used for the FHT and the QWE. New, this will be used according to the above
definitions.

- Bugfix in ``model.wavenumber`` for ``ab=[36, 63]`` (zeroes).


v1.5.x
""""""

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

**2018-04-25**

- DLF improvements:

- Digital linear filter (DLF) method for the Fourier transform can now be
carried out without spline, providing 0 for ``pts_per_dec`` (or any
integer smaller than 1).

- Combine kernel from ``fht`` and ``ffht`` into ``dlf``, hence separate DLF
from other calculations, as is done with QWE (``qwe`` for ``hqwe`` and
``fqwe``).

- Bug fix regarding ``transform.get_spline_values``; a DLF with
``pts_per_dec`` can now be shorter then the corresponding filter.

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

**2018-02-24**

- Documentation:

- Simplifications: avoid duplication as much as possible between the website
(empymod.github.io), the manual
(`empymod.readthedocs.io <https://empymod.readthedocs.io>`_), and the
``README`` (github.com/empymod/empymod).

- Website has now only *Features* and *Installation* in full, all other
information comes in the form of links.
- ``README`` has only information in the form of links.
- Manual contains the ``README``, and is basically the main document for
all information.

- Improvements: Change some remaining ``md``-syntax to ``rst``-syntax.

- FHT -> DLF: replace FHT as much as possible, without breaking backwards
compatibility.

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

**2018-01-02**

- Minimum parameter values can now be set and verified with
``utils.set_minimum`` and ``utils.get_minimum``.

- New Hankel filter ``wer_201_2018``.

- ``opt=parallel`` has no effect if ``numexpr`` is not built against Intel's
VML. (Use ``import numexpr; numexpr.use_vml`` to see if your ``numexpr`` uses
VML.)

- Bug fixes

- Version of manuscript submission to geophysics for the DLF article.


v1.4.x
""""""