Editing Gall–Peters projection (section)

===Simplified formula===
Stripping out unit conversion and uniform scaling, the formulae may be written:

:<math>\begin{align}
  x &= R\lambda\\
  y &= 2R\sin\varphi
\end{align}</math>

where ''<math>\lambda</math>'' is the longitude from the central meridian (in radians), ''<math>\varphi</math>'' is the latitude, and ''R'' is the radius of the globe used as the model of the earth for projection. Hence the sphere is mapped onto the vertical cylinder, and the cylinder is stretched to double its length. The stretch factor, 2 in this case, is what distinguishes the variations of cylindric equal-area projection.