/Proj4/PJ_moll.c
http://github.com/route-me/route-me · C · 65 lines · 62 code · 3 blank · 0 comment · 4 complexity · 3cdb293f3337fc05a14df961772e40b8 MD5 · raw file
- #ifndef lint
- static const char SCCSID[]="@(#)PJ_moll.c 4.1 94/02/15 GIE REL";
- #endif
- #define PROJ_PARMS__ \
- double C_x, C_y, C_p;
- #define PJ_LIB__
- #include "projects.h"
- PROJ_HEAD(moll, "Mollweide") "\n\tPCyl., Sph.";
- PROJ_HEAD(wag4, "Wagner IV") "\n\tPCyl., Sph.";
- PROJ_HEAD(wag5, "Wagner V") "\n\tPCyl., Sph.";
- #define MAX_ITER 10
- #define LOOP_TOL 1e-7
- FORWARD(s_forward); /* spheroid */
- double k, V;
- int i;
- k = P->C_p * sin(lp.phi);
- for (i = MAX_ITER; i ; --i) {
- lp.phi -= V = (lp.phi + sin(lp.phi) - k) /
- (1. + cos(lp.phi));
- if (fabs(V) < LOOP_TOL)
- break;
- }
- if (!i)
- lp.phi = (lp.phi < 0.) ? -HALFPI : HALFPI;
- else
- lp.phi *= 0.5;
- xy.x = P->C_x * lp.lam * cos(lp.phi);
- xy.y = P->C_y * sin(lp.phi);
- return (xy);
- }
- INVERSE(s_inverse); /* spheroid */
- double th, s;
- lp.phi = aasin(xy.y / P->C_y);
- lp.lam = xy.x / (P->C_x * cos(lp.phi));
- lp.phi += lp.phi;
- lp.phi = aasin((lp.phi + sin(lp.phi)) / P->C_p);
- return (lp);
- }
- FREEUP; if (P) pj_dalloc(P); }
- static PJ *
- setup(PJ *P, double p) {
- double r, sp, p2 = p + p;
- P->es = 0;
- sp = sin(p);
- r = sqrt(TWOPI * sp / (p2 + sin(p2)));
- P->C_x = 2. * r / PI;
- P->C_y = r / sp;
- P->C_p = p2 + sin(p2);
- P->inv = s_inverse;
- P->fwd = s_forward;
- return P;
- }
- ENTRY0(moll) ENDENTRY(setup(P, HALFPI))
- ENTRY0(wag4) ENDENTRY(setup(P, PI/3.))
- ENTRY0(wag5)
- P->es = 0;
- P->C_x = 0.90977;
- P->C_y = 1.65014;
- P->C_p = 3.00896;
- P->inv = s_inverse;
- P->fwd = s_forward;
- ENDENTRY(P)