# =========================================================
# calculate the number of feet and meters in degree or
# fraction of a degree arc given the earth's circumference
# ---------------------------------------------------------
# the calculations assume the earth is a perfect sphere
# (the earth is a pear shaped oblate spheroid)
# =========================================================
# -- constants
CIR = 24901.0 # circumference of earth in miles
FML = 5280.0 # feet in a mile
FMT = 3.28084 # feet in a meter
DEG = 360.0 # degrees in a circle
# --- calculate some constants
cf = CIR * FML # circumference of earth in feet
cm = cf / FMT # circumference of earth in meters
df = cf / DEG # one degree of arc in feet
dm = cm / DEG # one degree of arc in meters
print('')
print('circumference of earth {} feet'.format(cf))
print('circumference of earth {} meters'.format(cm))
print('One degree of arc {} feet'.format(df))
print('One meter of arc {} meters'.format(dm))
# --- probably need to put the following code in a loop so
# --- a user can input degrees and calculate more that once
calcdeg = 0.0010 # degrees to be calculated
ft = df * calcdeg # feet in calcdeg
mt = dm * calcdeg # meters in calcdeg
# -- display data
print('')
print('-- Calculating degrees of arc (Earth Circumference) --')
print(' degrees = {}'.format(calcdeg))
print(' feet = {}'.format(ft))
print(' meters = {}'.format(mt))