Latest changes for error and perf checking

ch-13/4.3-monte-carlo_perf/display_arena.py

@@ -0,0 +1,16 @@
+from matplotlib import pyplot as plt
+
+from robot import arena
+
+print(arena.distance_grid.min(), arena.distance_grid.max())
+for line in arena.boundary_lines:
+    plt.plot([line[0][0], line[1][0]], [line[0][1], line[1][1]], color="black")
+overscan_size = arena.overscan * arena.grid_cell_size
+plt.imshow(
+    arena.distance_grid.T,
+    extent = [-overscan_size, arena.width + overscan_size, -overscan_size, arena.height + overscan_size], 
+    origin="lower",
+    cmap="gray"
+)
+
+plt.show()