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#define PJ_LIB__
#include <errno.h>
#include <math.h>
#include "proj.h"
#include "projects.h"
struct pj_opaque {
double qp;
double *apa;
};
PROJ_HEAD(cea, "Equal Area Cylindrical") "\n\tCyl, Sph&Ell\n\tlat_ts=";
# define EPS 1e-10
static XY e_forward (LP lp, PJ *P) { /* Ellipsoidal, forward */
XY xy = {0.0,0.0};
xy.x = P->k0 * lp.lam;
xy.y = 0.5 * pj_qsfn (sin (lp.phi), P->e, P->one_es) / P->k0;
return xy;
}
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
xy.x = P->k0 * lp.lam;
xy.y = sin(lp.phi) / P->k0;
return xy;
}
static LP e_inverse (XY xy, PJ *P) { /* Ellipsoidal, inverse */
LP lp = {0.0,0.0};
lp.phi = pj_authlat(asin( 2. * xy.y * P->k0 / P->opaque->qp), P->opaque->apa);
lp.lam = xy.x / P->k0;
return lp;
}
static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */
LP lp = {0.0,0.0};
double t;
if ((t = fabs(xy.y *= P->k0)) - EPS <= 1.) {
if (t >= 1.)
lp.phi = xy.y < 0. ? -M_HALFPI : M_HALFPI;
else
lp.phi = asin(xy.y);
lp.lam = xy.x / P->k0;
} else {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return lp;
}
return (lp);
}
static void *destructor (PJ *P, int errlev) { /* Destructor */
if (0==P)
return 0;
if (0==P->opaque)
return pj_default_destructor (P, errlev);
pj_dealloc (P->opaque->apa);
return pj_default_destructor (P, errlev);
}
PJ *PROJECTION(cea) {
double t = 0.0;
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return pj_default_destructor (P, ENOMEM);
P->opaque = Q;
P->destructor = destructor;
if (pj_param(P->ctx, P->params, "tlat_ts").i) {
P->k0 = cos(t = pj_param(P->ctx, P->params, "rlat_ts").f);
if (P->k0 < 0.)
return pj_default_destructor (P, PJD_ERR_LAT_TS_LARGER_THAN_90);
}
if (P->es != 0.0) {
t = sin(t);
P->k0 /= sqrt(1. - P->es * t * t);
P->e = sqrt(P->es);
if (!(Q->apa = pj_authset(P->es)))
return pj_default_destructor(P, ENOMEM);
Q->qp = pj_qsfn(1., P->e, P->one_es);
P->inv = e_inverse;
P->fwd = e_forward;
} else {
P->inv = s_inverse;
P->fwd = s_forward;
}
return P;
}
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