/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

  1. #ifndef lint
  2. static const char SCCSID[]="@(#)PJ_moll.c 4.1 94/02/15 GIE REL";
  3. #endif
  4. #define PROJ_PARMS__ \
  5. double C_x, C_y, C_p;
  6. #define PJ_LIB__
  7. #include "projects.h"
  8. PROJ_HEAD(moll, "Mollweide") "\n\tPCyl., Sph.";
  9. PROJ_HEAD(wag4, "Wagner IV") "\n\tPCyl., Sph.";
  10. PROJ_HEAD(wag5, "Wagner V") "\n\tPCyl., Sph.";
  11. #define MAX_ITER 10
  12. #define LOOP_TOL 1e-7
  13. FORWARD(s_forward); /* spheroid */
  14. double k, V;
  15. int i;
  16. k = P->C_p * sin(lp.phi);
  17. for (i = MAX_ITER; i ; --i) {
  18. lp.phi -= V = (lp.phi + sin(lp.phi) - k) /
  19. (1. + cos(lp.phi));
  20. if (fabs(V) < LOOP_TOL)
  21. break;
  22. }
  23. if (!i)
  24. lp.phi = (lp.phi < 0.) ? -HALFPI : HALFPI;
  25. else
  26. lp.phi *= 0.5;
  27. xy.x = P->C_x * lp.lam * cos(lp.phi);
  28. xy.y = P->C_y * sin(lp.phi);
  29. return (xy);
  30. }
  31. INVERSE(s_inverse); /* spheroid */
  32. double th, s;
  33. lp.phi = aasin(xy.y / P->C_y);
  34. lp.lam = xy.x / (P->C_x * cos(lp.phi));
  35. lp.phi += lp.phi;
  36. lp.phi = aasin((lp.phi + sin(lp.phi)) / P->C_p);
  37. return (lp);
  38. }
  39. FREEUP; if (P) pj_dalloc(P); }
  40. static PJ *
  41. setup(PJ *P, double p) {
  42. double r, sp, p2 = p + p;
  43. P->es = 0;
  44. sp = sin(p);
  45. r = sqrt(TWOPI * sp / (p2 + sin(p2)));
  46. P->C_x = 2. * r / PI;
  47. P->C_y = r / sp;
  48. P->C_p = p2 + sin(p2);
  49. P->inv = s_inverse;
  50. P->fwd = s_forward;
  51. return P;
  52. }
  53. ENTRY0(moll) ENDENTRY(setup(P, HALFPI))
  54. ENTRY0(wag4) ENDENTRY(setup(P, PI/3.))
  55. ENTRY0(wag5)
  56. P->es = 0;
  57. P->C_x = 0.90977;
  58. P->C_y = 1.65014;
  59. P->C_p = 3.00896;
  60. P->inv = s_inverse;
  61. P->fwd = s_forward;
  62. ENDENTRY(P)