Refactor grid discretisation initialisation

gprMax/model.py

@@ -20,6 +20,7 @@ import datetime
 import itertools
 import logging
 import sys
+from typing import Tuple
 
 import humanize
 import numpy as np
@@ -160,6 +161,10 @@ class Model:
             if grid.snapshots:
                 save_snapshots(grid)
 
+    def set_grid_discretisation(self, point: Tuple[float, float, float]):
+        self.G.dl = np.array(point)
+        self.G.dx, self.G.dy, self.G.dz = point
+
     def solve(self, solver):
         """Solve using FDTD method.