tiny update

nifty_gridder.cc

@@ -138,9 +138,9 @@ Class storing UVW coordinates and channel information.
 
 Parameters
 ==========
-coord: np.array((nrows, 3), dtype=np.float)
+coord: np.array((nrows, 3), dtype=np.float64)
     u, v and w coordinates for each row
-freq: np.array((nchannels,), dtype=np.float)
+freq: np.array((nchannels,), dtype=np.float64)
     frequency for each individual channel (in Hz)
 )""";
 class PyBaselines: public Baselines