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

gall.c

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

static double scale;

static int
Xgall(struct place *place, double *x, double *y)
{
      /* two ways to compute tan(place->nlat.l/2) */
      if(fabs(place->nlat.s)<.1)
            *y = sin(place->nlat.l/2)/cos(place->nlat.l/2);
      else
            *y = (1-place->nlat.c)/place->nlat.s;
      *x = -scale*place->wlon.l;
      return 1;
}

proj
gall(double par)
{
      double coshalf;
      if(fabs(par)>80)
            return 0;
      par *= RAD;
      coshalf = cos(par/2);
      scale = cos(par)/(2*coshalf*coshalf);
      return Xgall;
}

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