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#define PJ_LIB__
#include <projects.h>
PROJ_HEAD(merc, "Mercator") "\n\tCyl, Sph&Ell\n\tlat_ts=";
#define EPS10 1.e-10
static XY e_forward (LP lp, PJ *P) { /* Ellipsoidal, forward */
XY xy = {0.0,0.0};
if (fabs(fabs(lp.phi) - HALFPI) <= EPS10)
F_ERROR;
xy.x = P->k0 * lp.lam;
xy.y = - P->k0 * log(pj_tsfn(lp.phi, sin(lp.phi), P->e));
return xy;
}
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
if (fabs(fabs(lp.phi) - HALFPI) <= EPS10)
F_ERROR;
xy.x = P->k0 * lp.lam;
xy.y = P->k0 * log(tan(FORTPI + .5 * lp.phi));
return xy;
}
static LP e_inverse (XY xy, PJ *P) { /* Ellipsoidal, inverse */
LP lp = {0.0,0.0};
if ((lp.phi = pj_phi2(P->ctx, exp(- xy.y / P->k0), P->e)) == HUGE_VAL)
I_ERROR;
lp.lam = xy.x / P->k0;
return lp;
}
static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */
LP lp = {0.0,0.0};
lp.phi = HALFPI - 2. * atan(exp(-xy.y / P->k0));
lp.lam = xy.x / P->k0;
return lp;
}
static void freeup(PJ *P) { /* Destructor */
pj_dealloc(P);
}
PJ *PROJECTION(merc) {
double phits=0.0;
int is_phits;
if( (is_phits = pj_param(P->ctx, P->params, "tlat_ts").i) ) {
phits = fabs(pj_param(P->ctx, P->params, "rlat_ts").f);
if (phits >= HALFPI) E_ERROR(-24);
}
if (P->es) { /* ellipsoid */
if (is_phits)
P->k0 = pj_msfn(sin(phits), cos(phits), P->es);
P->inv = e_inverse;
P->fwd = e_forward;
}
else { /* sphere */
if (is_phits)
P->k0 = cos(phits);
P->inv = s_inverse;
P->fwd = s_forward;
}
return P;
}
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