Update of document and docstring for the method from grid address to grid point

doc/hdf5_howto.rst

@@ -322,3 +322,19 @@ For example, :math:`\kappa_{\lambda,{xx}}` is calculated by::
    Out[9]:
    array([  1.02050201e+03,   1.02050201e+03,   1.02050201e+03,
             4.40486209e-15,   0.00000000e+00,  -4.40486209e-15])
+
+How to know grid point number corresponding to grid address
+------------------------------------------------------------
+
+Runngin with ``--write-gamma``, hdf5 files are written out file names
+with grid point numbers such as ``kappa-m202020-g4200.hdf5``. You may
+want to know the grid point number with given grid address. This is
+done using ``get_grid_point_from_address`` as follows::
+
+   In [1]: from phono3py.phonon3.triplets import get_grid_point_from_address
+
+   In [2]: get_grid_point_from_address([0, 10, 10], [20, 20, 20])
+   Out[2]: 4200
+
+Here the first argument of this method is the grid address and the
+second argument is the mesh numbers.

phono3py/phonon3/triplets.py

@@ -29,10 +29,6 @@ def get_triplets_at_q(grid_point,
         Mesh numbers
         dtype='intc'
         shape=(3,)
-    mesh : array_like
-        Mesh numbers
-        dtype='intc'
-        shape=(3,)
     point_group : array_like
         Rotation matrices in real space. Note that those in reciprocal space
         mean these matrices transposed (local terminology).
@@ -186,6 +182,26 @@ def get_grid_point_from_address_py(address, mesh):
 
 
 def get_grid_point_from_address(address, mesh):
+    """Grid point number is given by grid address.
+
+    Parameters
+    ----------
+    address : array_like
+        Grid address.
+        dtype='intc'
+        shape=(3,)
+    mesh : array_like
+        Mesh numbers.
+        dtype='intc'
+        shape=(3,)
+
+    Returns
+    -------
+    int
+        Grid point number.
+
+    """
+
     return spg.get_grid_point_from_address(address, mesh)