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

mercator.c

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

static int
Xmercator(struct place *place, double *x, double *y)
{
      if(fabs(place->nlat.l) > 80.*RAD)
            return(-1);
      *x = -place->wlon.l;
      *y = 0.5*log((1+place->nlat.s)/(1-place->nlat.s));
      return(1);
}

proj
mercator(void)
{
      return(Xmercator);
}

static double ecc = ECC;

static int
Xspmercator(struct place *place, double *x, double *y)
{
      if(Xmercator(place,x,y) < 0)
            return(-1);
      *y += 0.5*ecc*log((1-ecc*place->nlat.s)/(1+ecc*place->nlat.s));
      return(1);
}

proj
sp_mercator(void)
{
      return(Xspmercator);
}

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