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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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static double scale;
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static int
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Xgall(struct place *place, double *x, double *y)
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{
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	/* two ways to compute tan(place->nlat.l/2) */
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	if(fabs(place->nlat.s)<.1)
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		*y = sin(place->nlat.l/2)/cos(place->nlat.l/2);
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	else
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		*y = (1-place->nlat.c)/place->nlat.s;
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	*x = -scale*place->wlon.l;
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	return 1;
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}
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proj
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gall(double par)
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{
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	double coshalf;
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	if(fabs(par)>80)
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		return 0;
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	par *= RAD;
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	coshalf = cos(par/2);
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	scale = cos(par)/(2*coshalf*coshalf);
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	return Xgall;
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}