-- UTM WGS84 projection

-- northings and eastings coordinates of origin (metres)

n0=0
e0=500000

-- latitude of origin (radians, N positive)

k0=0

-- longitude of origin (radians, E positive)
-- depends on zone number zn

l0=(6*zn-183)*pi/180

-- equatorial and polar radii (metres)
-- multiplied by projection scale factor

a1=6375585.7
b1=6354209.6

-- calculated parameters

n1=(a1-b1)/(a1+b1)
e2=1-(b1/a1)^2