Merge remote-tracking branch 'origin/argmax_rays' into cubewcs_mosaic…

…_and_dask_reproject

spectral_cube/spectral_cube.py

@@ -1064,7 +1064,7 @@ def apply_function(self, function, axis=None, weights=None, unit=None,
         # check dtype first (for argmax/argmin)
         result = function(np.arange(3, dtype=self._data.dtype), **kwargs)
         if 'int' in str(result.dtype):
-            out = np.zeros([nz, nx, ny], dtype=dtype)
+            out = np.zeros([nz, nx, ny], dtype=result.dtype)
         else:
             out = np.empty([nz, nx, ny]) * np.nan