C Conversions to and from the geo (geographic) and the map C (Map-oriented) coordinate systems. C C The geo system is a 3-D Cartesian coordinate system, with origin C at the Center of the Earth, with the x_3 axis pointing to the North C Pole, the x_1 axis pointing to the Equator at the Greenwich Meridian, C and the x_2 axis by the right hand rule pointing to the Equator C at 90 E. C C In the map system, the axis of the map projection passes through the C center of the Earth, and through a point on the surface that acts as the c "Pole" of the map (Which will coincide with the North or South Pole, C unless the projection is Oblique or Transverse). The x_3 axis of the C map coordinate system is aligned with this map pole. In Lambert and C Mercator projections, a "Cut" extends from the map pole along a great C circle to its antipode; the unrolled map is discontinuous there. The C x_1 axis of the map coordinate system is diametrically opposite this C cut, and 90 degrees from the pole; the x_2 axis is selected to complete C a right hand rule. C C The coefficients of the map coordinate system relative to the geo system C are given in elements 2 through 10 of the stcprm array. C subroutine basg2m(stcprm, xin, xout) C receives the vector xin, giving the components of a point in the geo C system; returns xout, the components of the same point in the map system. dimension stcprm(15),xin(3),xout(3) ifind(l,k) = -2 + 3*l + k do k=1,3 xout(k) = 0. enddo do l=1,3 do k=1,3 xout(l) = xout(l) + xin(k) * stcprm(ifind(l,k)) enddo enddo return end