Below is the syntax highlighted version of greatcircle.py
from §1.2 Built-in Types of Data.
#----------------------------------------------------------------------- # greatcircle.py #----------------------------------------------------------------------- import stdio import sys import math # Accept float command-line arguments x1, y1, x2, and y2: the latitude # and longitude, in degrees, of two points on the earth. Compute and # write to standard output the great circle distance (in nautical # miles) between those two points. x1 = float(sys.argv[1]) y1 = float(sys.argv[2]) x2 = float(sys.argv[3]) y2 = float(sys.argv[4]) # The following formulas assume that angles are expressed in radians. # So convert to radians. x1 = math.radians(x1) y1 = math.radians(y1) x2 = math.radians(x2) y2 = math.radians(y2) # Compute using the law of cosines. # Great circle distance in radians angle1 = math.acos(math.sin(x1) * math.sin(x2) \ + math.cos(x1) * math.cos(x2) * math.cos(y1 - y2)) # Convert back to degrees. angle1 = math.degrees(angle1) # Each degree on a great circle of Earth is 60 nautical miles. distance1 = 60.0 * angle1 stdio.writeln(str(distance1) + ' nautical miles') # Compute using the Haversine formula. a = math.sin((x2-x1)/2.0) ** 2.0 \ + (math.cos(x1) * math.cos(x2) * (math.sin((y2-y1)/2.0) ** 2.0)) # Great circle distance in radians angle2 = 2.0 * math.asin(min(1.0, math.sqrt(a))) # Convert back to degrees. angle2 = math.degrees(angle2) # Each degree on a great circle of Earth is 60 nautical miles. distance2 = 60.0 * angle2 stdio.writeln(str(distance2) + ' nautical miles') #----------------------------------------------------------------------- # Leningrad to SF # python greatcircle.py 59.9 -30.3 37.8 122.4 # 4784.369673474519 nautical miles # 4784.369673474519 nautical miles # # Paris to Austin # python greatcircle.py 48.87 -2.33 30.27 97.74 # 4423.14075970742 nautical miles # 4423.140759707421 nautical miles # # Nashville airport (BNA) to LAX # python greatcircle.py 36.12 -86.67 33.94 -118.4 # 1557.505111036951 nautical miles # 1557.5051110369507 nautical miles # # Princeton to Paris # python greatcircle.py 40.35 74.65 48.87 -2.33 # 3185.1779271158425 nautical miles # 3185.1779271158416 nautical miles