/Proj4/PJ_eck2.c
C | 31 lines | 31 code | 0 blank | 0 comment | 5 complexity | 94bd3e0bb9e2fcd1ba69100bb04aa537 MD5 | raw file
1#ifndef lint 2static const char SCCSID[]="@(#)PJ_eck2.c 4.1 94/02/15 GIE REL"; 3#endif 4#define PJ_LIB__ 5# include "projects.h" 6PROJ_HEAD(eck2, "Eckert II") "\n\tPCyl. Sph."; 7#define FXC 0.46065886596178063902 8#define FYC 1.44720250911653531871 9#define C13 0.33333333333333333333 10#define ONEEPS 1.0000001 11FORWARD(s_forward); /* spheroid */ 12 xy.x = FXC * lp.lam * (xy.y = sqrt(4. - 3. * sin(fabs(lp.phi)))); 13 xy.y = FYC * (2. - xy.y); 14 if ( lp.phi < 0.) xy.y = -xy.y; 15 return (xy); 16} 17INVERSE(s_inverse); /* spheroid */ 18 lp.lam = xy.x / (FXC * ( lp.phi = 2. - fabs(xy.y) / FYC) ); 19 lp.phi = (4. - lp.phi * lp.phi) * C13; 20 if (fabs(lp.phi) >= 1.) { 21 if (fabs(lp.phi) > ONEEPS) I_ERROR 22 else 23 lp.phi = lp.phi < 0. ? -HALFPI : HALFPI; 24 } else 25 lp.phi = asin(lp.phi); 26 if (xy.y < 0) 27 lp.phi = -lp.phi; 28 return (lp); 29} 30FREEUP; if (P) pj_dalloc(P); } 31ENTRY0(eck2); P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)