Note: These formulas have been transcribed from EPSG Guidance Note #7-2. Users are encouraged to use that document rather than the text which follows as reference because limitations in the transcription will be avoided.¶¶This method has one of the simplest formulas available. If the latitude of natural origin (latO) is at the equator the method is also known as Plate Carrée. It is not used for rigorous topographic mapping because its distortion characteristics are unsuitable. Formulas are included to distinguish this map projection method from an approach sometimes mistakenly called by the same name and used for simple computer display of geographic coordinates – see Pseudo Plate Carrée (coordinate operation method code 9825).¶¶For the forward calculation:¶¶X =  R . (lon - lonO) . cos(latO)¶Y =  R .  lat¶¶where R = ((a^2 * (1 –  e^2)) / (1 – e^2 sin^2 latO)^2)^0.5¶and latO, lonO, lat and lon are expressed in radians.¶¶For the Equidistant Cylindrical method on a sphere (not ellipsoid), e = 0 and R = a.¶¶For the reverse calculation:¶¶lat = Y / R  ¶lon = lonO + (X / R cos(latO))¶¶where R is as for the forward method.