PJ_gn_sinu.c
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#ifndef lint
static const char SCCSID[]="@(#)PJ_gn_sinu.c 4.1 94/02/15 GIE REL";
#endif
#define PROJ_PARMS__ \
double *en; \
double m, n, C_x, C_y;
#define PJ_LIB__
#include "projects.h"
PROJ_HEAD(gn_sinu, "General Sinusoidal Series") "\n\tPCyl, Sph.\n\tm= n=";
PROJ_HEAD(sinu, "Sinusoidal (Sanson-Flamsteed)") "\n\tPCyl, Sph&Ell";
PROJ_HEAD(eck6, "Eckert VI") "\n\tPCyl, Sph.";
PROJ_HEAD(mbtfps, "McBryde-Thomas Flat-Polar Sinusoidal") "\n\tPCyl, Sph.";
#define EPS10 1e-10
#define MAX_ITER 8
#define LOOP_TOL 1e-7
/* Ellipsoidal Sinusoidal only */
FORWARD(e_forward); /* ellipsoid */
double s, c;
xy.y = pj_mlfn(lp.phi, s = sin(lp.phi), c = cos(lp.phi), P->en);
xy.x = lp.lam * c / sqrt(1. - P->es * s * s);
return (xy);
}
INVERSE(e_inverse); /* ellipsoid */
double s;
if ((s = fabs(lp.phi = pj_inv_mlfn(xy.y, P->es, P->en))) < HALFPI) {
s = sin(lp.phi);
lp.lam = xy.x * sqrt(1. - P->es * s * s) / cos(lp.phi);
} else if ((s - EPS10) < HALFPI)
lp.lam = 0.;
else I_ERROR;
return (lp);
}
/* General spherical sinusoidals */
FORWARD(s_forward); /* sphere */
if (!P->m)
lp.phi = P->n != 1. ? aasin(P->n * sin(lp.phi)): lp.phi;
else {
double k, V;
int i;
k = P->n * sin(lp.phi);
for (i = MAX_ITER; i ; --i) {
lp.phi -= V = (P->m * lp.phi + sin(lp.phi) - k) /
(P->m + cos(lp.phi));
if (fabs(V) < LOOP_TOL)
break;
}
if (!i)
F_ERROR
}
xy.x = P->C_x * lp.lam * (P->m + cos(lp.phi));
xy.y = P->C_y * lp.phi;
return (xy);
}
INVERSE(s_inverse); /* sphere */
double s;
xy.y /= P->C_y;
lp.phi = P->m ? aasin((P->m * xy.y + sin(xy.y)) / P->n) :
( P->n != 1. ? aasin(sin(xy.y) / P->n) : xy.y );
lp.lam = xy.x / (P->C_x * (P->m + cos(xy.y)));
return (lp);
}
FREEUP; if (P) { if (P->en) pj_dalloc(P->en); pj_dalloc(P); } }
static void /* for spheres, only */
setup(PJ *P) {
P->es = 0;
P->C_x = (P->C_y = sqrt((P->m + 1.) / P->n))/(P->m + 1.);
P->inv = s_inverse;
P->fwd = s_forward;
}
ENTRY1(sinu, en)
if (!(P->en = pj_enfn(P->es)))
E_ERROR_0;
if (P->es) {
P->inv = e_inverse;
P->fwd = e_forward;
} else {
P->n = 1.;
P->m = 0.;
setup(P);
}
ENDENTRY(P)
ENTRY1(eck6, en)
P->m = 1.;
P->n = 2.570796326794896619231321691;
setup(P);
ENDENTRY(P)
ENTRY1(mbtfps, en)
P->m = 0.5;
P->n = 1.785398163397448309615660845;
setup(P);
ENDENTRY(P)
ENTRY1(gn_sinu, en)
if (pj_param(P->params, "tn").i && pj_param(P->params, "tm").i) {
P->n = pj_param(P->params, "dn").f;
P->m = pj_param(P->params, "dm").f;
} else
E_ERROR(-99)
setup(P);
ENDENTRY(P)