Rename variable `lat_for_conv` to latitude

Trajectories/cost_function.py

@@ -183,8 +183,8 @@ for edge in g.edges():
     source_node = edge.source()
     target_node = edge.target()
 
-    lat_for_conv = math.radians((g.vp.pos_last[source_node][1] +
-                                 g.vp.pos_first[target_node][1]) / 2)
+    latitude = math.radians((g.vp.pos_last[source_node][1] +
+                             g.vp.pos_first[target_node][1]) / 2)
     # (latitude needed for conversion of degrees to kilometers)
 
     # Because of the wrapping issue (360° wrapping incorrectly to 0°),
@@ -193,7 +193,7 @@ for edge in g.edges():
                    - g.vp.pos_first[target_node][0])
     if lon_diff > 300: lon_diff = 360 - lon_diff
 
-    Delta_Cent = math.sqrt((lon_diff * 111.32 * math.cos(lat_for_conv))**2
+    Delta_Cent = math.sqrt((lon_diff * 111.32 * math.cos(latitude))**2
                            + ((g.vp.pos_last[source_node][1]
                                - g.vp.pos_first[target_node][1]) * 110.574)**2)