From 9f52d19a6b3f8e9805f89347de1fca5bbbe7681d Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 15:46:17 -0700
Subject: [PATCH 01/16] Old bug doesn't set "minor" for beams when
 array_finalize is used

---
 radio_beam/multiple_beams.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/radio_beam/multiple_beams.py b/radio_beam/multiple_beams.py
index dc7d2df..af88fd0 100644
--- a/radio_beam/multiple_beams.py
+++ b/radio_beam/multiple_beams.py
@@ -144,7 +144,7 @@ def __array_finalize__(self, obj):
 
         if isinstance(obj, Beams):
             self.major = obj.major
-            self.minajor = obj.minor
+            self.minor = obj.minor
             self.pa = obj.pa
             self.meta = obj.meta
 

From 52108fef6b9cc65e45906795398b9c6d5f6fb1d4 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 15:53:22 -0700
Subject: [PATCH 02/16] Beams arithmetic doesn't really work, and we don't
 really need it to either

---
 radio_beam/tests/test_beams.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/radio_beam/tests/test_beams.py b/radio_beam/tests/test_beams.py
index bf21d66..d3d6fbd 100644
--- a/radio_beam/tests/test_beams.py
+++ b/radio_beam/tests/test_beams.py
@@ -91,6 +91,20 @@ def test_indexing():
     assert np.all(beams[mask].major.value == majors[mask].value)
 
 
+# Arithmetic like this only works for circular beams
+# Keep commented out for now.
+# def test_beams_arithmetic():
+
+#     beams, majors = symm_beams_for_tests()[:2]
+
+#     areas = 2 * np.pi / (8 * np.log(2)) * (majors.to(u.rad)**2).to(u.sr)
+
+#     new_beams = beams * 2
+
+#     assert np.all(areas.value == beams.sr.value)
+#     assert np.all(beams.value == beams.sr.value)
+
+
 def test_average_beams():
 
     beams, majors = symm_beams_for_tests()[:2]

From a0305156b4154c3696913c25716a185d065765c0 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 16:27:20 -0700
Subject: [PATCH 03/16] Try correcting the major and minor axes when operations
 use array_finalize

---
 radio_beam/multiple_beams.py   | 11 +++++++++--
 radio_beam/tests/test_beams.py | 14 ++++++++------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/radio_beam/multiple_beams.py b/radio_beam/multiple_beams.py
index af88fd0..a0d5243 100644
--- a/radio_beam/multiple_beams.py
+++ b/radio_beam/multiple_beams.py
@@ -143,11 +143,18 @@ def __array_finalize__(self, obj):
                 self._set_unit(unit)
 
         if isinstance(obj, Beams):
-            self.major = obj.major
-            self.minor = obj.minor
+            # Multiplication and division should change the area,
+            # but not the PA or major/minor ratio
+            sqrt_ratios = np.sqrt(obj.sr / self.sr)
+
+            self.major = sqrt_ratios * obj.major
+            self.minor = sqrt_ratios * obj.minor
+
             self.pa = obj.pa
             self.meta = obj.meta
 
+            self.sr = obj.sr
+
         # Copy info if the original had `info` defined.  Because of the way the
         # DataInfo works, `'info' in obj.__dict__` is False until the
         # `info` attribute is accessed or set.  Note that `obj` can be an
diff --git a/radio_beam/tests/test_beams.py b/radio_beam/tests/test_beams.py
index d3d6fbd..245cc87 100644
--- a/radio_beam/tests/test_beams.py
+++ b/radio_beam/tests/test_beams.py
@@ -93,16 +93,18 @@ def test_indexing():
 
 # Arithmetic like this only works for circular beams
 # Keep commented out for now.
-# def test_beams_arithmetic():
+def test_beams_arithmetic():
 
-#     beams, majors = symm_beams_for_tests()[:2]
+    beams, majors = symm_beams_for_tests()[:2]
 
-#     areas = 2 * np.pi / (8 * np.log(2)) * (majors.to(u.rad)**2).to(u.sr)
+    new_beams = beams * 2
 
-#     new_beams = beams * 2
+    assert np.all(new_beams.sr.value == 2 * beams.sr.value)
 
-#     assert np.all(areas.value == beams.sr.value)
-#     assert np.all(beams.value == beams.sr.value)
+    sqrt_2 = np.sqrt(2)
+    # Major and minor axes should be sqrt(2) larger
+    assert np.all(new_beams.major.value == sqrt_2 * beams.major.value)
+    assert np.all(new_beams.minor.value == sqrt_2 * beams.minor.value)
 
 
 def test_average_beams():

From eae3a8573a1d72416d8ff4d3a73ec000deb9d314 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 17:52:05 -0700
Subject: [PATCH 04/16] Set arithmetic operations for Beams matching what Beam
 does

---
 radio_beam/multiple_beams.py | 78 ++++++++++++++++++++++++++++++++----
 radio_beam/utils.py          |  4 ++
 2 files changed, 74 insertions(+), 8 deletions(-)

diff --git a/radio_beam/multiple_beams.py b/radio_beam/multiple_beams.py
index a0d5243..bd2550b 100644
--- a/radio_beam/multiple_beams.py
+++ b/radio_beam/multiple_beams.py
@@ -8,6 +8,7 @@
 
 from .beam import Beam, _to_area, SIGMA_TO_FWHM
 from .commonbeam import commonbeam
+from .utils import InvalidBeamOperationError
 
 
 class Beams(u.Quantity):
@@ -16,7 +17,8 @@ class Beams(u.Quantity):
     """
 
     def __new__(cls, major=None, minor=None, pa=None,
-                areas=None, default_unit=u.arcsec, meta=None):
+                areas=None, default_unit=u.arcsec, meta=None,
+                beams=None):
         """
         Create a new set of Gaussian beams
 
@@ -34,12 +36,20 @@ def __new__(cls, major=None, minor=None, pa=None,
             Gaussian beam.
         default_unit : :class:`~astropy.units.Unit`
             The unit to impose on major, minor if they are specified as floats
+        beams : List of :class:`~radio_beam.Beam` objects
+            List of individual `Beam` objects. The resulting `Beams` object will
+            have major and minor axes in degrees.
         """
 
         # improve to some kwargs magic later
 
         # error checking
 
+        if beams is not None:
+            major = [beam.major.to(u.deg).value for beam in beams] * u.deg
+            minor = [beam.major.to(u.deg).value for beam in beams] * u.deg
+            pa = [beam.pa.to(u.deg).value for beam in beams] * u.deg
+
         # ... given an area make a round beam assuming it is Gaussian
         if areas is not None:
             rad = np.sqrt(areas / (2 * np.pi)) * u.deg
@@ -145,16 +155,11 @@ def __array_finalize__(self, obj):
         if isinstance(obj, Beams):
             # Multiplication and division should change the area,
             # but not the PA or major/minor ratio
-            sqrt_ratios = np.sqrt(obj.sr / self.sr)
-
-            self.major = sqrt_ratios * obj.major
-            self.minor = sqrt_ratios * obj.minor
-
+            self.major = obj.major
+            self.minor = obj.minor
             self.pa = obj.pa
             self.meta = obj.meta
 
-            self.sr = obj.sr
-
         # Copy info if the original had `info` defined.  Because of the way the
         # DataInfo works, `'info' in obj.__dict__` is False until the
         # `info` attribute is accessed or set.  Note that `obj` can be an
@@ -332,3 +337,60 @@ def common_beam(self, includemask=None, method='pts', **kwargs):
     def __iter__(self):
         for i in range(len(self)):
             yield self[i]
+
+    def __mul__(self, other):
+        # Other must be a single beam. Assume multiplying is convolving
+        # as set of beams with a given beam
+        if not isinstance(other, Beam):
+            raise InvalidBeamOperationError("Multiplication is defined as a "
+                                            "convolution of the set of beams "
+                                            "with a given beam. Must be "
+                                            "multiplied with a Beam object.")
+
+        return Beams(beams=[beam * other for beam in self])
+
+    def __div__(self, other):
+        # Other must be a single beam. Assume dividing is deconvolving
+        # as set of beams with a given beam
+        if not isinstance(other, Beam):
+            raise InvalidBeamOperationError("Division is defined as a "
+                                            "deconvolution of the set of beams"
+                                            " with a given beam. Must be "
+                                            "divided by a Beam object.")
+
+        return Beams(beams=[beam - other for beam in self])
+
+    def __add__(self, other):
+        raise InvalidBeamOperationError("Addition of a set of Beams "
+                                        "is not defined.")
+
+    def __sub__(self, other):
+        raise InvalidBeamOperationError("Addition of a set of Beams "
+                                        "is not defined.")
+
+    def __eq__(self, other):
+        # other should be a single beam, or a another Beams object
+        if isinstance(other, Beam):
+            return np.array([beam == other for beam in self])
+        elif isinstance(other, Beams):
+            # These should have the same size.
+            if not self.size == other.size:
+                raise InvalidBeamOperationError("Beams objects must have the "
+                                                "same shape to test "
+                                                "equality.")
+
+            return np.all([beam == other_beam for beam, other_beam in
+                           zip(self, other)])
+        else:
+            raise InvalidBeamOperationError("Must test equality with a Beam"
+                                            " or Beams object.")
+
+    def __ne__(self, other):
+        eq_out = self.__eq__(other)
+
+        # If other is a Beam, will get array back
+        if isinstance(eq_out, np.ndarray):
+            return ~eq_out
+        # If other is a Beams, will get boolean back
+        else:
+            return not eq_out
diff --git a/radio_beam/utils.py b/radio_beam/utils.py
index 1ac419a..8d83dea 100644
--- a/radio_beam/utils.py
+++ b/radio_beam/utils.py
@@ -8,6 +8,10 @@ class BeamError(Exception):
     pass
 
 
+class InvalidBeamOperationError(Exception):
+    pass
+
+
 def deconvolve(beam, other, failure_returns_pointlike=False):
     """
     Deconvolve a beam from another

From 5f78e849b2e0d7a12bdc437353a9231366a4e870 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 18:06:54 -0700
Subject: [PATCH 05/16] Make dividing also give deconvolution in Beam

---
 radio_beam/beam.py            | 3 +++
 radio_beam/tests/test_beam.py | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/radio_beam/beam.py b/radio_beam/beam.py
index 716b743..e38241e 100644
--- a/radio_beam/beam.py
+++ b/radio_beam/beam.py
@@ -348,6 +348,9 @@ def __mul__(self, other):
     def __sub__(self, other):
         return self.deconvolve(other)
 
+    def __truediv__(self, other):
+        return self.deconvolve(other)
+
     def deconvolve(self, other, failure_returns_pointlike=False):
         """
         Deconvolve a beam from another
diff --git a/radio_beam/tests/test_beam.py b/radio_beam/tests/test_beam.py
index adfc5c8..3b0b9f6 100644
--- a/radio_beam/tests/test_beam.py
+++ b/radio_beam/tests/test_beam.py
@@ -247,6 +247,10 @@ def test_conv_deconv():
     assert beam2 == beam3 - beam1
     assert beam1 == beam3 - beam2
 
+    # Dividing should give the same thing
+    assert beam2 == beam3 / beam1
+    assert beam1 == beam3 / beam2
+
     assert beam3 == beam1 * beam2
 
 

From 503170162fe71354b6c0203d40aafe030af95dd8 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 18:07:26 -0700
Subject: [PATCH 06/16] Need to use truediv

---
 radio_beam/multiple_beams.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/radio_beam/multiple_beams.py b/radio_beam/multiple_beams.py
index bd2550b..b806b4c 100644
--- a/radio_beam/multiple_beams.py
+++ b/radio_beam/multiple_beams.py
@@ -349,7 +349,7 @@ def __mul__(self, other):
 
         return Beams(beams=[beam * other for beam in self])
 
-    def __div__(self, other):
+    def __truediv__(self, other):
         # Other must be a single beam. Assume dividing is deconvolving
         # as set of beams with a given beam
         if not isinstance(other, Beam):

From f81a179d6405adf5d253a5db92c2a7ecf2458d45 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 18:08:17 -0700
Subject: [PATCH 07/16] Add a bunch of operation tests for Beams

---
 radio_beam/tests/test_beams.py | 106 +++++++++++++++++++++++++++++----
 1 file changed, 94 insertions(+), 12 deletions(-)

diff --git a/radio_beam/tests/test_beams.py b/radio_beam/tests/test_beams.py
index 245cc87..38b521f 100644
--- a/radio_beam/tests/test_beams.py
+++ b/radio_beam/tests/test_beams.py
@@ -9,6 +9,7 @@
 from ..multiple_beams import Beams
 from ..beam import Beam
 from ..commonbeam import common_2beams, common_manybeams_mve
+from ..utils import InvalidBeamOperationError
 
 from .test_beam import data_path
 
@@ -62,6 +63,97 @@ def test_beams_from_fits_bintable():
     assert (beams.pa.value == bintable.data['BPA']).all()
 
 
+def test_beams_from_list_of_beam():
+
+    beams, majors = symm_beams_for_tests()[:2]
+
+    new_beams = Beams(beams=[beam for beam in beams])
+
+    assert beams == new_beams
+
+
+def test_beams_equality_beams():
+
+    beams, majors = symm_beams_for_tests()[:2]
+
+    assert beams == beams
+
+    assert not beams != beams
+
+    abeams, amajors = asymm_beams_for_tests()[:2]
+
+    assert not (beams == abeams)
+
+    assert beams != abeams
+
+
+def test_beams_equality_beam():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beam = Beam(1 * u.arcsec)
+
+    assert np.all(beams == beam)
+
+    assert not np.any(beams != beam)
+
+
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_equality_fail():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beams == 2
+
+
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_notequality_fail():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beams != 2
+
+
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_equality_fail_shape():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    assert np.all(beams == beams[1:])
+
+
+def test_beams_mult_convolution():
+
+    beams, majors = asymm_beams_for_tests()[:2]
+
+    beam = Beam(1 * u.arcsec)
+
+    conv_beams = beams * beam
+
+    individ_conv_beams = [beam_i.convolve(beam) for beam_i in beams]
+    new_beams = Beams(beams=individ_conv_beams)
+
+    assert conv_beams == new_beams
+
+
+def test_beams_div_deconvolution():
+
+    beams, majors = asymm_beams_for_tests()[:2]
+
+    beam = Beam(0.25 * u.arcsec)
+
+    deconv_beams = beams / beam
+
+    individ_deconv_beams = [beam_i.deconvolve(beam) for beam_i in beams]
+    new_beams = Beams(beams=individ_deconv_beams)
+
+    assert deconv_beams == new_beams
+
+
 def test_indexing():
 
     beams, majors = symm_beams_for_tests()[:2]
@@ -91,20 +183,10 @@ def test_indexing():
     assert np.all(beams[mask].major.value == majors[mask].value)
 
 
-# Arithmetic like this only works for circular beams
-# Keep commented out for now.
-def test_beams_arithmetic():
-
-    beams, majors = symm_beams_for_tests()[:2]
-
-    new_beams = beams * 2
+# def test_beams_mult_convolution():
 
-    assert np.all(new_beams.sr.value == 2 * beams.sr.value)
+#     beams, majors = symm_beams_for_tests()[:2]
 
-    sqrt_2 = np.sqrt(2)
-    # Major and minor axes should be sqrt(2) larger
-    assert np.all(new_beams.major.value == sqrt_2 * beams.major.value)
-    assert np.all(new_beams.minor.value == sqrt_2 * beams.minor.value)
 
 
 def test_average_beams():

From 424f57ec82ec64b5ea8efcccdea3e56fd71b9fd7 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 18:12:40 -0700
Subject: [PATCH 08/16] Add more simple operation tests for failures

---
 radio_beam/tests/test_beams.py | 35 ++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/radio_beam/tests/test_beams.py b/radio_beam/tests/test_beams.py
index 38b521f..82dae72 100644
--- a/radio_beam/tests/test_beams.py
+++ b/radio_beam/tests/test_beams.py
@@ -125,6 +125,41 @@ def test_beams_equality_fail_shape():
 
     assert np.all(beams == beams[1:])
 
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_add_fail():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beams + 2
+
+
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_sub_fail():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beams - 2
+
+
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_mult_fail():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beams * 2
+
+
+@pytest.mark.xfail(raises=InvalidBeamOperationError, strict=True)
+def test_beams_div_fail():
+
+    # Test whether all are equal to a single beam
+    beams = Beams([1.] * 5 * u.arcsec)
+
+    beams / 2
+
 
 def test_beams_mult_convolution():
 

From b37b21ee7abb8fb1ad885cfb0d62602b35ca0ad8 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 18:33:58 -0700
Subject: [PATCH 09/16] Update conftest

---
 radio_beam/conftest.py | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/radio_beam/conftest.py b/radio_beam/conftest.py
index 10cac21..bdaf64c 100644
--- a/radio_beam/conftest.py
+++ b/radio_beam/conftest.py
@@ -2,8 +2,19 @@
 # by importing them here in conftest.py they are discoverable by py.test
 # no matter how it is invoked within the source tree.
 
-from astropy.tests.pytest_plugins import *
+from astropy.version import version as astropy_version
+if astropy_version < '3.0':
+    # With older versions of Astropy, we actually need to import the pytest
+    # plugins themselves in order to make them discoverable by pytest.
+    from astropy.tests.pytest_plugins import *
+else:
+    # As of Astropy 3.0, the pytest plugins provided by Astropy are
+    # automatically made available when Astropy is installed. This means it's
+    # not necessary to import them here, but we still need to import global
+    # variables that are used for configuration.
+    from astropy.tests.plugins.display import PYTEST_HEADER_MODULES, TESTED_VERSIONS
 
+from astropy.tests.helper import enable_deprecations_as_exceptions
 ## Uncomment the following line to treat all DeprecationWarnings as
 ## exceptions
 # enable_deprecations_as_exceptions()

From 3f2996aafd3871c23747fe74285e33cbd0763f59 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 18:36:57 -0700
Subject: [PATCH 10/16] Drop testing np <1.13 with py3.5. Critical older
 versions (like for CASA) are already tested

---
 .travis.yml | 2 --
 1 file changed, 2 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 7ca71a3..f58e0a4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -96,8 +96,6 @@ matrix:
         # versions of Python, we can vary Python and Numpy versions at the same
         # time.
 
-        - os: linux
-          env: PYTHON_VERSION=3.5 NUMPY_VERSION=1.12
         - os: linux
           env: PYTHON_VERSION=3.6 NUMPY_VERSION=1.13
         - os: linux

From d592320f7eab0b8c9205fdd1e4ff43a3fa17e1f9 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 19:06:48 -0700
Subject: [PATCH 11/16] Issue in setup.cfg??

---
 setup.cfg | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.cfg b/setup.cfg
index 74ebf1c..a7d27ec 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -7,7 +7,7 @@ all_files = 1
 upload-dir = docs/_build/html
 show-response = 1
 
-[pytest]
+[tool:pytest]
 minversion = 2.2
 norecursedirs = build docs/_build
 doctest_plus = enabled

From 04837ffcbbe4416e8aa918f9194ca6a78c84394c Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Wed, 16 Jan 2019 21:59:28 -0700
Subject: [PATCH 12/16] Update CHANGE [skip ci]

---
 CHANGES.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CHANGES.rst b/CHANGES.rst
index f2da6d9..b037ae9 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,5 +1,8 @@
 0.3 (unreleased)
 ----------------
+ - Set mult/div for convolution/deconvolution in `Beam` and `Beams`.
+   The `==` and `!=` operators also work with `Beams` now.
+   (https://github.com/radio-astro-tools/radio-beam/pull/75)
  - Added common beam operations to `Beams`.
    (https://github.com/radio-astro-tools/radio-beam/pull/67)
  - Fix PA usage for plotting and kernel routines.

From 5b5f9c60cd0c468b9e8442528d28f8247ca278b0 Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Thu, 17 Jan 2019 10:42:02 -0700
Subject: [PATCH 13/16] Use div for deconvolution

---
 radio_beam/multiple_beams.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/radio_beam/multiple_beams.py b/radio_beam/multiple_beams.py
index b806b4c..3e9dbed 100644
--- a/radio_beam/multiple_beams.py
+++ b/radio_beam/multiple_beams.py
@@ -358,7 +358,7 @@ def __truediv__(self, other):
                                             " with a given beam. Must be "
                                             "divided by a Beam object.")
 
-        return Beams(beams=[beam - other for beam in self])
+        return Beams(beams=[beam / other for beam in self])
 
     def __add__(self, other):
         raise InvalidBeamOperationError("Addition of a set of Beams "

From ba390c85b52ed7b0e17ee284275c4f504475876f Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Thu, 17 Jan 2019 10:52:04 -0700
Subject: [PATCH 14/16] Add deprecation warning for
 subtraction-as-deconvolution

---
 radio_beam/beam.py            |  5 ++++-
 radio_beam/tests/test_beam.py | 16 ++++++++++++++--
 radio_beam/utils.py           |  4 ++++
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/radio_beam/beam.py b/radio_beam/beam.py
index e38241e..a62d9a7 100644
--- a/radio_beam/beam.py
+++ b/radio_beam/beam.py
@@ -12,7 +12,7 @@
 from astropy.convolution import Kernel2D
 from astropy.convolution.kernels import _round_up_to_odd_integer
 
-from .utils import deconvolve, convolve
+from .utils import deconvolve, convolve, RadioBeamDeprecationWarning
 
 # Conversion between a twod Gaussian FWHM**2 and effective area
 FWHM_TO_AREA = 2*np.pi/(8*np.log(2))
@@ -346,6 +346,9 @@ def __mul__(self, other):
 
     # Does division do the same? Or what? Doesn't have to be defined.
     def __sub__(self, other):
+        warnings.warn("Subtraction-as-deconvolution is deprecated. "
+                      "Use division instead.",
+                      RadioBeamDeprecationWarning)
         return self.deconvolve(other)
 
     def __truediv__(self, other):
diff --git a/radio_beam/tests/test_beam.py b/radio_beam/tests/test_beam.py
index 3b0b9f6..c737bbd 100644
--- a/radio_beam/tests/test_beam.py
+++ b/radio_beam/tests/test_beam.py
@@ -6,6 +6,7 @@
 from astropy.io import fits
 from astropy import units as u
 import os
+import warnings
 import numpy as np
 import numpy.testing as npt
 from astropy.tests.helper import assert_quantity_allclose
@@ -17,6 +18,9 @@
 except ImportError:
     HAS_CASA = False
 
+from ..utils import RadioBeamDeprecationWarning
+
+
 data_dir = os.path.join(os.path.dirname(__file__), 'data')
 
 
@@ -244,8 +248,16 @@ def test_conv_deconv():
     assert beam1.convolve(beam2) == beam2.convolve(beam1)
 
     # Test multiplication and subtraction (i.e., convolution and deconvolution)
-    assert beam2 == beam3 - beam1
-    assert beam1 == beam3 - beam2
+    # subtraction-as-deconvolution is deprecated. Check that one of the gives
+    # the warning
+
+    with warnings.catch_warnings(record=True) as w:
+        assert beam2 == beam3 - beam1
+
+    assert len(w) == 1
+    assert w[0].category == RadioBeamDeprecationWarning
+    assert str(w[0].message) == ("Subtraction-as-deconvolution is deprecated. "
+                                 "Use division instead.")
 
     # Dividing should give the same thing
     assert beam2 == beam3 / beam1
diff --git a/radio_beam/utils.py b/radio_beam/utils.py
index 8d83dea..50acd5a 100644
--- a/radio_beam/utils.py
+++ b/radio_beam/utils.py
@@ -12,6 +12,10 @@ class InvalidBeamOperationError(Exception):
     pass
 
 
+class RadioBeamDeprecationWarning(Warning):
+    pass
+
+
 def deconvolve(beam, other, failure_returns_pointlike=False):
     """
     Deconvolve a beam from another

From 01413db9e69def1c9b5937a825c26e37c09117cc Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Thu, 17 Jan 2019 10:53:27 -0700
Subject: [PATCH 15/16] Remove old commented out deconvolution test

---
 radio_beam/tests/test_beams.py | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/radio_beam/tests/test_beams.py b/radio_beam/tests/test_beams.py
index 82dae72..0b9c7dc 100644
--- a/radio_beam/tests/test_beams.py
+++ b/radio_beam/tests/test_beams.py
@@ -218,12 +218,6 @@ def test_indexing():
     assert np.all(beams[mask].major.value == majors[mask].value)
 
 
-# def test_beams_mult_convolution():
-
-#     beams, majors = symm_beams_for_tests()[:2]
-
-
-
 def test_average_beams():
 
     beams, majors = symm_beams_for_tests()[:2]

From 24092c60589b6984432b5915cc4063e6d69de8aa Mon Sep 17 00:00:00 2001
From: e-koch <koch.eric.w@gmail.com>
Date: Thu, 17 Jan 2019 11:11:19 -0700
Subject: [PATCH 16/16] Enable coveralls

---
 .travis.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index f58e0a4..d0cc2a5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -151,4 +151,4 @@ script:
 after_success:
     # If coveralls.io is set up for this package, uncomment the line below.
     # The coveragerc file may be customized as needed for your package.
-    # - if [[ $SETUP_CMD == *coverage* ]]; then coveralls --rcfile='packagename/tests/coveragerc'; fi
+    - if [[ $SETUP_CMD == *coverage* ]]; then coveralls --rcfile='radio_beam/tests/coveragerc'; fi