Before revision: Definition The natural Earth is defined by the following formulas: , where x∈ -2.73539, 2.73539 and y∈ -1.42239, 1.42239 are the Cartesian coordinates; ∈ -, is the longitude from the central meridian in radians; φ∈ -/2, /2 is the latitude in radians; l(φ) is the length of the parallel at latitude φ; d(φ) is the distance of the parallel from the equator at latitude φ .
After revision: Definition The natural Earth is defined by the following formulas: , where x∈ -2.73539, 2.73539 and y∈ and are the Cartesian coordinates; ∈ -, is the longitude from the central meridian in radians; φ∈ -/2, /2 is the latitude in radians; l(φ) is the length of the parallel at latitude ; is the distance of the parallel from the equator at latitude .