fix dtype issue in complex data insertion (#14)

src/torch_image_lerp/linear_interpolation_3d.py

@@ -119,12 +119,12 @@ def insert_into_image_3d(
     data, coordinates = data[inside], coordinates[inside]
 
     # calculate and cache floor and ceil of coordinates for each data point being inserted
-    _c = torch.empty(size=(data.shape[0], 2, 3), dtype=torch.long, device=image.device)
+    _c = torch.empty(size=(data.shape[0], 2, 3), dtype=torch.int64, device=image.device)
     _c[:, 0] = torch.floor(coordinates)  # for lower corners
     _c[:, 1] = torch.ceil(coordinates)  # for upper corners
 
     # calculate linear interpolation weights for each data point being inserted
-    _w = torch.empty(size=(data.shape[0], 2, 3), dtype=image.dtype, device=image.device)  # (b, 2, zyx)
+    _w = torch.empty(size=(data.shape[0], 2, 3), dtype=torch.float64, device=image.device)  # (b, 2, zyx)
     _w[:, 1] = coordinates - _c[:, 0]  # upper corner weights
     _w[:, 0] = 1 - _w[:, 1]  # lower corner weights