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Annotation of researchv10no/cmd/map/libmap/elliptic.c, revision 1.1.1.1

1.1       root        1: #include "map.h"
                      2: 
                      3: struct coord center;
                      4: 
                      5: static int
                      6: Xelliptic(struct place *place, double *x, double *y)
                      7: {
                      8:        double r1,r2;
                      9:        r1 = acos(place->nlat.c*(place->wlon.c*center.c
                     10:                - place->wlon.s*center.s));
                     11:        r2 = acos(place->nlat.c*(place->wlon.c*center.c
                     12:                + place->wlon.s*center.s));
                     13:        *x = -(r1*r1 - r2*r2)/(4*center.l);
                     14:        *y = (r1*r1+r2*r2)/2 - (center.l*center.l+*x**x);
                     15:        if(*y < 0)
                     16:                *y = 0;
                     17:        *y = sqrt(*y);
                     18:        if(place->nlat.l<0)
                     19:                *y = -*y;
                     20:        return(1);
                     21: }
                     22: 
                     23: proj
                     24: elliptic(double l)
                     25: {
                     26:        l = fabs(l);
                     27:        if(l>89)
                     28:                return(0);
                     29:        if(l<1)
                     30:                return(Xazequidistant);
                     31:        deg2rad(l,&center);
                     32:        return(Xelliptic);
                     33: }

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