EPSG:9834

For the forward calculation for the normal aspect of the projection in which lat1 is the latitude of the standard parallel:

E =  FE   R (lon – lonO) cos(lat1)

N =  FN   R sin(lat) / cos(lat1)

where  lat1, lat and lon are expressed in radians

R is the radius of the sphere and will normally be one of the CRS parameters. If the figure of the earth used is an ellipsoid rather than a sphere then R should be calculated as the radius of the authalic sphere using the formula for RA given in EPSG Guidance Note 7-2, section 1.2, table 3.

For the reverse calculation:

lat = asin{[(N – FN) / R] cos(lat1)}

lon = lonO   {[E – FE] / [R cos(lat1)]}

where R is as for the forward method.

See information source for formulas for oblique and polar aspects and examples.