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

mollweide.c

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

static int
Xmollweide(struct place *place, double *x, double *y)
{
      double z;
      double w;
      z = place->nlat.l;
      if(fabs(z)<89.9*RAD)
            do {  /*newton for 2z+sin2z=pi*sin(lat)*/
                  w = (2*z+sin(2*z)-PI*place->nlat.s)/(2+2*cos(2*z));
                  z -= w;
            } while(fabs(w)>=.00001);
      *y = sin(z);
      *x = - (2/PI)*cos(z)*place->wlon.l;
      return(1);
}

proj
mollweide(void)
{
      return(Xmollweide);
}

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