29 lines
584 B
C
29 lines
584 B
C
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#include <u.h>
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#include <libc.h>
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#include "map.h"
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int
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Xpolyconic(struct place *place, double *x, double *y)
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{
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double r, alpha;
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double lat2, lon2;
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if(fabs(place->nlat.l) > .01) {
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r = place->nlat.c / place->nlat.s;
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alpha = place->wlon.l * place->nlat.s;
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*y = place->nlat.l + r*(1 - cos(alpha));
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*x = - r*sin(alpha);
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} else {
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lon2 = place->wlon.l * place->wlon.l;
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lat2 = place->nlat.l * place->nlat.l;
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*y = place->nlat.l * (1+(lon2/2)*(1-(8+lon2)*lat2/12));
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*x = - place->wlon.l * (1-lat2*(3+lon2)/6);
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}
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return(1);
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}
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proj
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polyconic(void)
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{
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return(Xpolyconic);
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}
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