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#define PJ_LIB__
#include <projects.h>
struct pj_opaque {
int vdg3;
};
PROJ_HEAD(vandg2, "van der Grinten II") "\n\tMisc Sph, no inv.";
PROJ_HEAD(vandg3, "van der Grinten III") "\n\tMisc Sph, no inv.";
#define TOL 1e-10
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double x1, at, bt, ct;
bt = fabs(M_TWO_D_PI * lp.phi);
if ((ct = 1. - bt * bt) < 0.)
ct = 0.;
else
ct = sqrt(ct);
if (fabs(lp.lam) < TOL) {
xy.x = 0.;
xy.y = M_PI * (lp.phi < 0. ? -bt : bt) / (1. + ct);
} else {
at = 0.5 * fabs(M_PI / lp.lam - lp.lam / M_PI);
if (Q->vdg3) {
x1 = bt / (1. + ct);
xy.x = M_PI * (sqrt(at * at + 1. - x1 * x1) - at);
xy.y = M_PI * x1;
} else {
x1 = (ct * sqrt(1. + at * at) - at * ct * ct) /
(1. + at * at * bt * bt);
xy.x = M_PI * x1;
xy.y = M_PI * sqrt(1. - x1 * (x1 + 2. * at) + TOL);
}
if ( lp.lam < 0.) xy.x = -xy.x;
if ( lp.phi < 0.) xy.y = -xy.y;
}
return xy;
}
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(vandg2) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return freeup_new (P);
P->opaque = Q;
Q->vdg3 = 0;
P->fwd = s_forward;
return P;
}
PJ *PROJECTION(vandg3) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return freeup_new (P);
P->opaque = Q;
Q->vdg3 = 1;
P->es = 0.;
P->fwd = s_forward;
return P;
}
#ifndef PJ_SELFTEST
int pj_vandg2_selftest (void) {return 0;}
#else
int pj_vandg2_selftest (void) {
double tolerance_lp = 1e-10;
double tolerance_xy = 1e-7;
char s_args[] = {"+proj=vandg2 +a=6400000 +lat_1=0.5 +lat_2=2"};
LP fwd_in[] = {
{ 2, 1},
{ 2,-1},
{-2, 1},
{-2,-1}
};
XY s_fwd_expect[] = {
{ 223395.24785043663, 111718.49103722633},
{ 223395.24785043663, -111718.49103722633},
{-223395.24785043663, 111718.49103722633},
{-223395.24785043663, -111718.49103722633},
};
return pj_generic_selftest (0, s_args, tolerance_xy, tolerance_lp, 4, 4, fwd_in, 0, s_fwd_expect, 0, 0, 0);
}
#endif
#ifndef PJ_SELFTEST
int pj_vandg3_selftest (void) {return 0;}
#else
int pj_vandg3_selftest (void) {
double tolerance_lp = 1e-10;
double tolerance_xy = 1e-7;
char s_args[] = {"+proj=vandg3 +a=6400000 +lat_1=0.5 +lat_2=2"};
LP fwd_in[] = {
{ 2, 1},
{ 2,-1},
{-2, 1},
{-2,-1}
};
XY s_fwd_expect[] = {
{ 223395.24955283134, 111704.51990442065},
{ 223395.24955283134, -111704.51990442065},
{-223395.24955283134, 111704.51990442065},
{-223395.24955283134, -111704.51990442065},
};
return pj_generic_selftest (0, s_args, tolerance_xy, tolerance_lp, 4, 4, fwd_in, 0, s_fwd_expect, 0, 0, 0);
}
#endif
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