[BUGFIX] GPU slicing

Fixes #90 (closed)

src/pystencils/gpu/indexing.py

@@ -226,7 +226,7 @@ class BlockIndexing(AbstractIndexing):
         end = [s.stop if s.stop != 0 else 1 for s in numeric_iteration_slice]
         for i, s in enumerate(numeric_iteration_slice):
             if s.step and s.step != 1:
-                end[i] = div_floor(end[i], s.step)
+                end[i] = div_ceil(s.stop - s.start, s.step) + s.start
 
         if self._dim < 4:
             conditions = [c < e for c, e in zip(self.coordinates, end)]