/Proj4/PJ_collg.c

http://github.com/route-me/route-me · C · 32 lines · 32 code · 0 blank · 0 comment · 6 complexity · a03681b22b038800402f19827eaa81b4 MD5 · raw file

  1. #ifndef lint
  2. static const char SCCSID[]="@(#)PJ_collg.c 4.1 94/02/15 GIE REL";
  3. #endif
  4. #define PJ_LIB__
  5. # include "projects.h"
  6. PROJ_HEAD(collg, "Collignon") "\n\tPCyl, Sph.";
  7. #define FXC 1.12837916709551257390
  8. #define FYC 1.77245385090551602729
  9. #define ONEEPS 1.0000001
  10. FORWARD(s_forward); /* spheroid */
  11. if ((xy.y = 1. - sin(lp.phi)) <= 0.)
  12. xy.y = 0.;
  13. else
  14. xy.y = sqrt(xy.y);
  15. xy.x = FXC * lp.lam * xy.y;
  16. xy.y = FYC * (1. - xy.y);
  17. return (xy);
  18. }
  19. INVERSE(s_inverse); /* spheroid */
  20. lp.phi = xy.y / FYC - 1.;
  21. if (fabs(lp.phi = 1. - lp.phi * lp.phi) < 1.)
  22. lp.phi = asin(lp.phi);
  23. else if (fabs(lp.phi) > ONEEPS) I_ERROR
  24. else lp.phi = lp.phi < 0. ? -HALFPI : HALFPI;
  25. if ((lp.lam = 1. - sin(lp.phi)) <= 0.)
  26. lp.lam = 0.;
  27. else
  28. lp.lam = xy.x / (FXC * sqrt(lp.lam));
  29. return (lp);
  30. }
  31. FREEUP; if (P) pj_dalloc(P); }
  32. ENTRY0(collg) P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)