Do not recompute Omega for each call

cost_function.py

@@ -26,6 +26,8 @@ import util_eddies
 import bisect
 import argparse
 
+Omega = 2 * math.pi / 86164.
+
 def calculate_radii_rossby(list_eddies, e_overestim, handlers, array_d_init):
     """Compute average on list_eddies of Rossby number and radius of
     maximum speed contour.
@@ -35,7 +37,6 @@ def calculate_radii_rossby(list_eddies, e_overestim, handlers, array_d_init):
     radii = 0 # in m
     rossby = 0
     n_valid_Rossby = 0
-    Omega = 2 * math.pi / 86164.
     n_eddies = len(list_eddies)
 
     for n in list_eddies: