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Sourcecode: r-cran-mapproj version File versions  Download package

polyconic.c

/* RSB #include <u.h>
#include <libc.h>*/
#include "map.h"

int
Xpolyconic(struct place *place, double *x, double *y)
{
      double r, alpha;
      double lat2, lon2;
      if(fabs(place->nlat.l) > .01) {
            r = place->nlat.c / place->nlat.s;
            alpha = place->wlon.l * place->nlat.s;
            *y = place->nlat.l + r*(1 - cos(alpha));
            *x = - r*sin(alpha);
      } else {
            lon2 = place->wlon.l * place->wlon.l;
            lat2 = place->nlat.l * place->nlat.l;
            *y = place->nlat.l * (1+(lon2/2)*(1-(8+lon2)*lat2/12));
            *x = - place->wlon.l * (1-lat2*(3+lon2)/6);
      }
      return(1);
}

proj
polyconic(void)
{
      return(Xpolyconic);
}

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