mdboom · Aug 26, 2014 · Jun 13, 2014 · Jul 24, 2014 · Aug 13, 2014 · embray
diff --git a/CHANGES.rst b/CHANGES.rst
@@ -158,6 +158,9 @@ Bug Fixes
 
 - ``astropy.units``
 
+  - Added a ``latex_inline`` unit format that returns the units in LaTeX math
+    notation with negative exponents instead of fractions [#2622].
+
 - ``astropy.utils``
 
 - ``astropy.vo``

diff --git a/astropy/units/format/__init__.py b/astropy/units/format/__init__.py
@@ -12,17 +12,16 @@
 from .cds import CDS
 from .console import Console
 from .fits import Fits
-from .latex import Latex
+from .latex import Latex, LatexInline
 from .ogip import OGIP
 from .unicode_format import Unicode
 from .vounit import VOUnit
 
 from ...extern.six import string_types
 
 __all__ = [
-    'Base', 'Generic', 'CDS', 'Console', 'Fits', 'Latex', 'OGIP', 'Unicode',
-    'Unscaled', 'VOUnit', 'get_format']
-
+    'Base', 'Generic', 'CDS', 'Console', 'Fits', 'Latex', 'LatexInline',
+    'OGIP', 'Unicode', 'Unscaled', 'VOUnit', 'get_format']
 
 def get_format(format=None):
     """

diff --git a/astropy/units/format/latex.py b/astropy/units/format/latex.py
@@ -9,6 +9,7 @@
 
 from . import base
 from . import utils
+from ...extern.six.moves import zip
 
 
 class Latex(base.Base):
@@ -55,6 +56,23 @@ def _format_exponential_notation(self, val):
 
         return r" \times ".join(parts)
 
+    def _format_bases(self, unit):
+        positives, negatives = utils.get_grouped_by_powers(
+                unit.bases, unit.powers)
+
+        if len(negatives):
+            if len(positives):
+                positives = self._format_unit_list(positives)
+            else:
+                positives = '1'
+            negatives = self._format_unit_list(negatives)
+            s = r'\frac{{{0}}}{{{1}}}'.format(positives, negatives)
+        else:
+            positives = self._format_unit_list(positives)
+            s = positives
+
+        return s
+
     def to_string(self, unit):
         from .. import core
 
@@ -71,19 +89,24 @@ def to_string(self, unit):
                 s = self._format_exponential_notation(unit.scale) + r'\,'
 
             if len(unit.bases):
-                positives, negatives = utils.get_grouped_by_powers(
-                    unit.bases, unit.powers)
-                if len(negatives):
-                    if len(positives):
-                        positives = self._format_unit_list(positives)
-                    else:
-                        positives = '1'
-                    negatives = self._format_unit_list(negatives)
-                    s += r'\frac{{{0}}}{{{1}}}'.format(positives, negatives)
-                else:
-                    positives = self._format_unit_list(positives)
-                    s += positives
+                s += self._format_bases(unit)
+
         elif isinstance(unit, core.NamedUnit):
             s = self._latex_escape(unit.name)
 
         return r'$\mathrm{{{0}}}$'.format(s)
+
+class LatexInline(Latex):
+    """
+    Output LaTeX to display the unit based on IAU style guidelines with negative
+    powers.
+
+    Attempts to follow the `IAU Style Manual
+    <http://www.iau.org/static/publications/stylemanual1989.pdf>`_ and the
+    `ApJ and AJ style guide
+    <http://aas.org/authors/manuscript-preparation-aj-apj-author-instructions>`_.
+    """
+    name = 'latex_inline'
+
+    def _format_bases(self, unit):
+        return self._format_unit_list(zip(unit.bases, unit.powers))
diff --git a/astropy/units/tests/test_format.py b/astropy/units/tests/test_format.py
@@ -263,6 +263,13 @@ def test_new_style_latex():
     fluxunit = u.erg / (u.cm ** 2 * u.s)
     assert "{0:latex}".format(fluxunit) == r'$\mathrm{\frac{erg}{s\,cm^{2}}}$'
 
+def test_latex_scale():
+    latex = '$\\mathrm{2.1798721 \\times 10^{-18}\\,\\frac{m^{2}\\,kg}{s^{2}}}$'
+    assert u.Ry.decompose().to_string('latex') == latex
+
+def test_latex_inline_scale():
+    latex_inline = '$\\mathrm{2.1798721 \\times 10^{-18}\\,m^{2}\\,kg\\,s^{-2}}$'
+    assert u.Ry.decompose().to_string('latex_inline') == latex_inline
 
 def test_format_styles():
     fluxunit = u.erg / (u.cm ** 2 * u.s)
@@ -274,6 +281,7 @@ def _test_format_styles(format_spec, s):
         ('s', 'erg / (cm2 s)'),
         ('console', '  erg  \n ------\n s cm^2'),
         ('latex', '$\\mathrm{\\frac{erg}{s\\,cm^{2}}}$'),
+        ('latex_inline', '$\\mathrm{erg\\,s^{-1}\\,cm^{-2}}$'),
         ('>20s','       erg / (cm2 s)'),
     ]
 

diff --git a/docs/units/format.rst b/docs/units/format.rst
@@ -152,6 +152,20 @@ following formats:
 
        \mathrm{\frac{erg}{s\,cm^{2}}}
 
+  - ``"latex_inline"``: Writes units out using LaTeX math syntax using the
+    `IAU Style Manual
+    <http://www.iau.org/static/publications/stylemanual1989.pdf>`__
+    recommendations for unit presentation, using negative powers instead of
+    fractions, as required by some journals (e.g., `Apj and AJ
+    <http://aas.org/authors/manuscript-preparation-aj-apj-author-instructions#_Toc2.2>`_.)
+    Best suited for unit representation inline with text::
+
+      >>> fluxunit.to_string('latex_inline')  # doctest: +SKIP
+
+    .. math::
+
+       \mathrm{erg\,s^{-1}\,cm^{-2}}
+
   - ``"console"``: Writes a multi-line representation of the unit
     useful for display in a text console::