31 lines
468 B
C
31 lines
468 B
C
#include <u.h>
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#include <libc.h>
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#include "map.h"
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static int
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Xlagrange(struct place *place, double *x, double *y)
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{
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double z1,z2;
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double w1,w2,t1,t2;
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struct place p;
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copyplace(place,&p);
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if(place->nlat.l<0) {
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p.nlat.l = -p.nlat.l;
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p.nlat.s = -p.nlat.s;
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}
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Xstereographic(&p,&z1,&z2);
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csqrt(-z2/2,z1/2,&w1,&w2);
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cdiv(w1-1,w2,w1+1,w2,&t1,&t2);
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*y = -t1;
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*x = t2;
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if(place->nlat.l<0)
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*y = -*y;
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return(1);
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}
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proj
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lagrange(void)
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{
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return(Xlagrange);
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}
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