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#define PJ_LIB__
#include <projects.h>
PROJ_HEAD(fouc_s, "Foucaut Sinusoidal") "\n\tPCyl., Sph.";
#define MAX_ITER 10
#define LOOP_TOL 1e-7
struct pj_opaque {
double n, n1;
};
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double t;
t = cos(lp.phi);
xy.x = lp.lam * t / (Q->n + Q->n1 * t);
xy.y = Q->n * lp.phi + Q->n1 * sin(lp.phi);
return xy;
}
static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */
LP lp = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double V;
int i;
if (Q->n != 0.0) {
lp.phi = xy.y;
for (i = MAX_ITER; i ; --i) {
lp.phi -= V = (Q->n * lp.phi + Q->n1 * sin(lp.phi) - xy.y ) /
(Q->n + Q->n1 * cos(lp.phi));
if (fabs(V) < LOOP_TOL)
break;
}
if (!i)
lp.phi = xy.y < 0. ? -M_HALFPI : M_HALFPI;
} else
lp.phi = aasin(P->ctx,xy.y);
V = cos(lp.phi);
lp.lam = xy.x * (Q->n + Q->n1 * V) / V;
return lp;
}
static void *freeup_new (PJ *P) { /* Destructor */
if (0==P)
return 0;
if (0==P->opaque)
return pj_dealloc (P);
pj_dealloc (P->opaque);
return pj_dealloc(P);
}
static void freeup (PJ *P) {
freeup_new (P);
return;
}
PJ *PROJECTION(fouc_s) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return freeup_new (P);
P->opaque = Q;
Q->n = pj_param(P->ctx, P->params, "dn").f;
if (Q->n < 0. || Q->n > 1.)
E_ERROR(-99)
Q->n1 = 1. - Q->n;
P->es = 0;
P->inv = s_inverse;
P->fwd = s_forward;
return P;
}
#ifndef PJ_SELFTEST
int pj_fouc_s_selftest (void) {return 0;}
#else
int pj_fouc_s_selftest (void) {
double tolerance_lp = 1e-10;
double tolerance_xy = 1e-7;
char s_args[] = {"+proj=fouc_s +a=6400000 +lat_1=0.5 +lat_2=2"};
LP fwd_in[] = {
{ 2, 1},
{ 2,-1},
{-2, 1},
{-2,-1}
};
XY s_fwd_expect[] = {
{ 223402.14425527424, 111695.40119861449},
{ 223402.14425527424, -111695.40119861449},
{-223402.14425527424, 111695.40119861449},
{-223402.14425527424, -111695.40119861449},
};
XY inv_in[] = {
{ 200, 100},
{ 200,-100},
{-200, 100},
{-200,-100}
};
LP s_inv_expect[] = {
{ 0.0017904931097838226, 0.000895246554928339},
{ 0.0017904931097838226, -0.000895246554928339},
{-0.0017904931097838226, 0.000895246554928339},
{-0.0017904931097838226, -0.000895246554928339},
};
return pj_generic_selftest (0, s_args, tolerance_xy, tolerance_lp, 4, 4, fwd_in, 0, s_fwd_expect, inv_in, 0, s_inv_expect);
}
#endif
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