Merge remote-tracking branch 'upstream/develop' into multipole

docs/source/usersguide/input.rst

@@ -1066,6 +1066,20 @@ Each ``<cell>`` element can have the following attributes or sub-elements:
 
         <cell fill="..." rotation="0 0 90" />
 
+    The rotation applied is an intrinsic rotation whose Tait-Bryan angles are
+    given as those specified about the x, y, and z axes respectively. That is to
+    say, if the angles are :math:`(\phi, \theta, \psi)`, then the rotation
+    matrix applied is :math:`R_z(\psi) R_y(\theta) R_x(\phi)` or
+
+    .. math::
+
+       \left [ \begin{array}{ccc} \cos\theta \cos\psi & -\cos\theta \sin\psi +
+       \sin\phi \sin\theta \cos\psi & \sin\phi \sin\psi + \cos\phi \sin\theta
+       \cos\psi \\ \cos\theta \sin\psi & \cos\phi \cos\psi + \sin\phi \sin\theta
+       \sin\psi & -\sin\phi \cos\psi + \cos\phi \sin\theta \sin\psi \\
+       -\sin\theta & \sin\phi \cos\theta & \cos\phi \cos\theta \end{array}
+       \right ]
+
     *Default*: None
 
   :translation:
@@ -1248,11 +1262,10 @@ Each ``material`` element can have the following attributes or sub-elements:
     An element with attributes/sub-elements called ``value`` and ``units``. The
     ``value`` attribute is the numeric value of the density while the ``units``
     can be "g/cm3", "kg/m3", "atom/b-cm", "atom/cm3", or "sum". The "sum" unit
-    indicates that values appearing in ``ao`` attributes for ``<nuclide>`` and
-    ``<element>`` sub-elements are to be interpreted as nuclide/element
-    densities in atom/b-cm, and the total density of the material is taken as
-    the sum of all nuclides/elements. The "sum" option cannot be used in
-    conjunction with weight percents.  The "macro" unit is used with
+    indicates that values appearing in ``ao`` or ``wo`` attributes for ``<nuclide>``
+    and ``<element>`` sub-elements are to be interpreted as absolute nuclide/element
+    densities in atom/b-cm or g/cm3, and the total density of the material is
+    taken as the sum of all nuclides/elements. The "macro" unit is used with
     a ``macroscopic`` quantity to indicate that the density is already included
     in the library and thus not needed here.  However, if a value is provided
     for the ``value``, then this is treated as a number density multiplier on