import math
# ------------------------------------------------------------
# Convert degrees to radians
# ------------------------------------------------------------
def deg_to_rad(deg: float) -> float:
return deg * math.pi / 180.0
# ------------------------------------------------------------
# Compute the great-circle distance between two points on Earth
# using the Haversine formula.
# lat1, lon1, lat2, lon2 are in degrees.
# The result is returned in kilometers.
# ------------------------------------------------------------
def haversine(lat1: float, lon1: float,
lat2: float, lon2: float) -> float:
# Earth's mean radius in kilometers
R = 6371.0
# Convert all angles to radians
rlat1 = deg_to_rad(lat1)
rlon1 = deg_to_rad(lon1)
rlat2 = deg_to_rad(lat2)
rlon2 = deg_to_rad(lon2)
# Differences
dlat = rlat2 - rlat1
dlon = rlon2 - rlon1
# Haversine formula
# a is the Haversine of the central angle between the two points.
a = math.sin(dlat / 2)**2 + \
math.cos(rlat1) * math.cos(rlat2) * math.sin(dlon / 2)**2
# c is the central angle between the two points on the Earth’s surface.
c = 2 * math.asin(math.sqrt(a))
# Final distance
return R * c
# ------------------------------------------------------------
# Main
# ------------------------------------------------------------
if __name__ == "__main__":
# Example coordinates:
# Austin, Texas
lat1 = 30.2672
lon1 = -97.7431
# Houston, Texas
lat2 = 29.7604
lon2 = -95.3698
distance_km = haversine(lat1, lon1, lat2, lon2)
# Convert kilometers to miles
distance_miles = distance_km * 0.621371
print(f"Distance: {distance_km:.3f} km")
print(f"Distance: {distance_miles:.3f} miles")
"""
run:
Distance: 235.352 km
Distance: 146.241 miles
"""
