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#define PJ_LIB__
#include <errno.h>
#include <proj.h>
#include "projects.h"
PROJ_HEAD(loxim, "Loximuthal") "\n\tPCyl Sph";
#define EPS 1e-8
struct pj_opaque {
double phi1;
double cosphi1;
double tanphi1;
};
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
xy.y = lp.phi - Q->phi1;
if (fabs(xy.y) < EPS)
xy.x = lp.lam * Q->cosphi1;
else {
xy.x = M_FORTPI + 0.5 * lp.phi;
if (fabs(xy.x) < EPS || fabs(fabs(xy.x) - M_HALFPI) < EPS)
xy.x = 0.;
else
xy.x = lp.lam * xy.y / log( tan(xy.x) / Q->tanphi1 );
}
return xy;
}
static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */
LP lp = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
lp.phi = xy.y + Q->phi1;
if (fabs(xy.y) < EPS) {
lp.lam = xy.x / Q->cosphi1;
} else {
lp.lam = M_FORTPI + 0.5 * lp.phi;
if (fabs(lp.lam) < EPS || fabs(fabs(lp.lam) - M_HALFPI) < EPS)
lp.lam = 0.;
else
lp.lam = xy.x * log( tan(lp.lam) / Q->tanphi1 ) / xy.y ;
}
return lp;
}
PJ *PROJECTION(loxim) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return pj_default_destructor (P, ENOMEM);
P->opaque = Q;
Q->phi1 = pj_param(P->ctx, P->params, "rlat_1").f;
Q->cosphi1 = cos(Q->phi1);
if (Q->cosphi1 < EPS)
return pj_default_destructor(P, PJD_ERR_LAT_LARGER_THAN_90);
Q->tanphi1 = tan(M_FORTPI + 0.5 * Q->phi1);
P->inv = s_inverse;
P->fwd = s_forward;
P->es = 0.;
return P;
}
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