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#define PJ_LIB__
#include <float.h>
#include <math.h>
#include "proj_internal.h"
#include "proj.h"
#include "proj_math.h"
#include "projects.h"
PROJ_HEAD(merc, "Mercator") "\n\tCyl, Sph&Ell\n\tlat_ts=";
PROJ_HEAD(webmerc, "Web Mercator / Pseudo Mercator") "\n\tCyl, Ell\n\t";
#define EPS10 1.e-10
static double logtanpfpim1(double x) { /* log(tan(x/2 + M_FORTPI)) */
if (fabs(x) <= DBL_EPSILON) {
/* tan(M_FORTPI + .5 * x) can be approximated by 1.0 + x */
return log1p(x);
}
return log(tan(M_FORTPI + .5 * x));
}
static XY e_forward (LP lp, PJ *P) { /* Ellipsoidal, forward */
XY xy = {0.0,0.0};
if (fabs(fabs(lp.phi) - M_HALFPI) <= EPS10) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return xy;
}
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) - M_HALFPI) <= EPS10) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return xy;
}
xy.x = P->k0 * lp.lam;
xy.y = P->k0 * logtanpfpim1(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) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return lp;
}
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 = atan(sinh(xy.y / P->k0));
lp.lam = xy.x / P->k0;
return lp;
}
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 >= M_HALFPI)
return pj_default_destructor(P, PJD_ERR_LAT_TS_LARGER_THAN_90);
}
if (P->es != 0.0) { /* 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;
}
PJ *PROJECTION(webmerc) {
/* Overriding k_0 with fixed parameter */
P->k0 = 1.0;
P->inv = s_inverse;
P->fwd = s_forward;
return P;
}
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