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#define PJ_LIB__
#include <proj.h>
#include "projects.h"
PROJ_HEAD(hammer, "Hammer & Eckert-Greifendorff")
"\n\tMisc Sph, \n\tW= M=";
#define EPS 1.0e-10
struct pj_opaque {
double w; \
double m, rm;
};
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double cosphi, d;
d = sqrt(2./(1. + (cosphi = cos(lp.phi)) * cos(lp.lam *= Q->w)));
xy.x = Q->m * d * cosphi * sin(lp.lam);
xy.y = Q->rm * d * 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 z;
z = sqrt(1. - 0.25*Q->w*Q->w*xy.x*xy.x - 0.25*xy.y*xy.y);
if (fabs(2.*z*z-1.) < EPS) {
lp.lam = HUGE_VAL;
lp.phi = HUGE_VAL;
proj_errno_set(P, PJD_ERR_LAT_OR_LON_EXCEED_LIMIT);
} else {
lp.lam = aatan2(Q->w * xy.x * z,2. * z * z - 1)/Q->w;
lp.phi = aasin(P->ctx,z * xy.y);
}
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(hammer) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return freeup_new (P);
P->opaque = Q;
if (pj_param(P->ctx, P->params, "tW").i) {
if ((Q->w = fabs(pj_param(P->ctx, P->params, "dW").f)) <= 0.) {
proj_errno_set(P, PJD_ERR_W_OR_M_ZERO_OR_LESS);
return freeup_new(P);
}
} else
Q->w = .5;
if (pj_param(P->ctx, P->params, "tM").i) {
if ((Q->m = fabs(pj_param(P->ctx, P->params, "dM").f)) <= 0.) {
proj_errno_set(P, PJD_ERR_W_OR_M_ZERO_OR_LESS);
return freeup_new(P);
}
} else
Q->m = 1.;
Q->rm = 1. / Q->m;
Q->m /= Q->w;
P->es = 0.;
P->fwd = s_forward;
P->inv = s_inverse;
return P;
}
#ifndef PJ_SELFTEST
int pj_hammer_selftest (void) {return 0;}
#else
int pj_hammer_selftest (void) {
double tolerance_lp = 1e-10;
double tolerance_xy = 1e-7;
char s_args[] = {"+proj=hammer +a=6400000 +lat_1=0.5 +lat_2=2"};
LP fwd_in[] = {
{ 2, 1},
{ 2,-1},
{-2, 1},
{-2,-1}
};
XY s_fwd_expect[] = {
{ 223373.78870324057, 111703.90739776699},
{ 223373.78870324057, -111703.90739776699},
{-223373.78870324057, 111703.90739776699},
{-223373.78870324057, -111703.90739776699},
};
XY inv_in[] = {
{ 200, 100},
{ 200,-100},
{-200, 100},
{-200,-100}
};
LP s_inv_expect[] = {
{ 0.001790493109965961, 0.00089524655487369749},
{ 0.001790493109965961, -0.00089524655487369749},
{-0.001790493109965961, 0.00089524655487369749},
{-0.001790493109965961, -0.00089524655487369749},
};
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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