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

simpleconic.c

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

static double r0, a;

static int
Xsimpleconic(struct place *place, double *x, double *y)
{
      double r = r0 - place->nlat.l;
      double t = a*place->wlon.l;
      *x = -r*sin(t);
      *y = -r*cos(t);
      return 1;
}

proj
simpleconic(double par0, double par1)
{
      struct coord lat0;
      struct coord lat1;
      deg2rad(par0,&lat0);
      deg2rad(par1,&lat1);
      if(fabs(lat0.l+lat1.l)<.01)
            return rectangular(par0);
      if(fabs(lat0.l-lat1.l)<.01) {
            a = lat0.s/lat0.l;
            r0 = lat0.c/lat0.s + lat0.l;
      } else {
            a = (lat1.c-lat0.c)/(lat0.l-lat1.l);
            r0 = ((lat0.c+lat1.c)/a + lat1.l + lat0.l)/2;
      }
      return Xsimpleconic;
}

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