/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. 

  2. static const char SCCSID[]="@(#)PJ_moll.c	4.1	94/02/15	GIE	REL";
    3. 

  3. #endif
    4. 

  4. #define PROJ_PARMS__ \
    5. 

  5. 	double	C_x, C_y, C_p;
    6. 

  6. #define PJ_LIB__
    7. 

  7. #include	"projects.h"
    8. 

  8. PROJ_HEAD(moll, "Mollweide") "\n\tPCyl., Sph.";
    9. 

  9. PROJ_HEAD(wag4, "Wagner IV") "\n\tPCyl., Sph.";
    10. 

  10. PROJ_HEAD(wag5, "Wagner V") "\n\tPCyl., Sph.";
    11. 

  11. #define MAX_ITER	10
    12. 

  12. #define LOOP_TOL	1e-7
    13. 

  13. FORWARD(s_forward); /* spheroid */
    14. 

  14. 	double k, V;
    15. 

  15. 	int i;
    16. 

  16. 

  17. 	k = P->C_p * sin(lp.phi);
    18. 

  18. 	for (i = MAX_ITER; i ; --i) {
    19. 

  19. 		lp.phi -= V = (lp.phi + sin(lp.phi) - k) /
    20. 

  20. 			(1. + cos(lp.phi));
    21. 

  21. 		if (fabs(V) < LOOP_TOL)
    22. 

  22. 			break;
    23. 

  23. 	}
    24. 

  24. 	if (!i)
    25. 

  25. 		lp.phi = (lp.phi < 0.) ? -HALFPI : HALFPI;
    26. 

  26. 	else
    27. 

  27. 		lp.phi *= 0.5;
    28. 

  28. 	xy.x = P->C_x * lp.lam * cos(lp.phi);
    29. 

  29. 	xy.y = P->C_y * sin(lp.phi);
    30. 

  30. 	return (xy);
    31. 

  31. }
    32. 

  32. INVERSE(s_inverse); /* spheroid */
    33. 

  33. 	double th, s;
    34. 

  34. 

  35. 	lp.phi = aasin(xy.y / P->C_y);
    36. 

  36. 	lp.lam = xy.x / (P->C_x * cos(lp.phi));
    37. 

  37. 	lp.phi += lp.phi;
    38. 

  38. 	lp.phi = aasin((lp.phi + sin(lp.phi)) / P->C_p);
    39. 

  39. 	return (lp);
    40. 

  40. }
    41. 

  41. FREEUP; if (P) pj_dalloc(P); }
    42. 

  42. 	static PJ *
    43. 

  43. setup(PJ *P, double p) {
    44. 

  44. 	double r, sp, p2 = p + p;
    45. 

  45. 

  46. 	P->es = 0;
    47. 

  47. 	sp = sin(p);
    48. 

  48. 	r = sqrt(TWOPI * sp / (p2 + sin(p2)));
    49. 

  49. 	P->C_x = 2. * r / PI;
    50. 

  50. 	P->C_y = r / sp;
    51. 

  51. 	P->C_p = p2 + sin(p2);
    52. 

  52. 	P->inv = s_inverse;
    53. 

  53. 	P->fwd = s_forward;
    54. 

  54. 	return P;
    55. 

  55. }
    56. 

  56. ENTRY0(moll) ENDENTRY(setup(P, HALFPI))
    57. 

  57. ENTRY0(wag4) ENDENTRY(setup(P, PI/3.))
    58. 

  58. ENTRY0(wag5)
    59. 

  59. 	P->es = 0;
    60. 

  60. 	P->C_x = 0.90977;
    61. 

  61. 	P->C_y = 1.65014;
    62. 

  62. 	P->C_p = 3.00896;
    63. 

  63. 	P->inv = s_inverse;
    64. 

  64. 	P->fwd = s_forward;
    65. 

  65. ENDENTRY(P)
    66.