/Proj4/PJ_oea.c

http://github.com/route-me/route-me · C · 61 lines · 59 code · 2 blank · 0 comment · 3 complexity · efb1d02b9481c856b20243ac4fdc01d0 MD5 · raw file 

    

  1. #ifndef lint
    2. 

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

  3. #endif
    4. 

  4. #define PROJ_PARMS__ \
    5. 

  5. 	double	theta; \
    6. 

  6. 	double	m, n; \
    7. 

  7. 	double	two_r_m, two_r_n, rm, rn, hm, hn; \
    8. 

  8. 	double	cp0, sp0;
    9. 

  9. #define PJ_LIB__
    10. 

  10. #include	"projects.h"
    11. 

  11. PROJ_HEAD(oea, "Oblated Equal Area") "\n\tMisc Sph\n\tn= m= theta=";
    12. 

  12. FORWARD(s_forward); /* sphere */
    13. 

  13. 	double Az, M, N, cp, sp, cl, shz;
    14. 

  14. 

  15. 	cp = cos(lp.phi);
    16. 

  16. 	sp = sin(lp.phi);
    17. 

  17. 	cl = cos(lp.lam);
    18. 

  18. 	Az = aatan2(cp * sin(lp.lam), P->cp0 * sp - P->sp0 * cp * cl) + P->theta;
    19. 

  19. 	shz = sin(0.5 * aacos(P->sp0 * sp + P->cp0 * cp * cl));
    20. 

  20. 	M = aasin(shz * sin(Az));
    21. 

  21. 	N = aasin(shz * cos(Az) * cos(M) / cos(M * P->two_r_m));
    22. 

  22. 	xy.y = P->n * sin(N * P->two_r_n);
    23. 

  23. 	xy.x = P->m * sin(M * P->two_r_m) * cos(N) / cos(N * P->two_r_n);
    24. 

  24. 	return (xy);
    25. 

  25. }
    26. 

  26. INVERSE(s_inverse); /* sphere */
    27. 

  27. 	double N, M, xp, yp, z, Az, cz, sz, cAz;
    28. 

  28. 

  29. 	N = P->hn * aasin(xy.y * P->rn);
    30. 

  30. 	M = P->hm * aasin(xy.x * P->rm * cos(N * P->two_r_n) / cos(N));
    31. 

  31. 	xp = 2. * sin(M);
    32. 

  32. 	yp = 2. * sin(N) * cos(M * P->two_r_m) / cos(M);
    33. 

  33. 	cAz = cos(Az = aatan2(xp, yp) - P->theta);
    34. 

  34. 	z = 2. * aasin(0.5 * hypot(xp, yp));
    35. 

  35. 	sz = sin(z);
    36. 

  36. 	cz = cos(z);
    37. 

  37. 	lp.phi = aasin(P->sp0 * cz + P->cp0 * sz * cAz);
    38. 

  38. 	lp.lam = aatan2(sz * sin(Az),
    39. 

  39. 		P->cp0 * cz - P->sp0 * sz * cAz);
    40. 

  40. 	return (lp);
    41. 

  41. }
    42. 

  42. FREEUP; if (P) pj_dalloc(P); }
    43. 

  43. ENTRY0(oea)
    44. 

  44. 	if (((P->n = pj_param(P->params, "dn").f) <= 0.) ||
    45. 

  45. 		((P->m = pj_param(P->params, "dm").f) <= 0.))
    46. 

  46. 		E_ERROR(-39)
    47. 

  47. 	else {
    48. 

  48. 		P->theta = pj_param(P->params, "rtheta").f;
    49. 

  49. 		P->sp0 = sin(P->phi0);
    50. 

  50. 		P->cp0 = cos(P->phi0);
    51. 

  51. 		P->rn = 1./ P->n;
    52. 

  52. 		P->rm = 1./ P->m;
    53. 

  53. 		P->two_r_n = 2. * P->rn;
    54. 

  54. 		P->two_r_m = 2. * P->rm;
    55. 

  55. 		P->hm = 0.5 * P->m;
    56. 

  56. 		P->hn = 0.5 * P->n;
    57. 

  57. 		P->fwd = s_forward;
    58. 

  58. 		P->inv = s_inverse;
    59. 

  59. 		P->es = 0.;
    60. 

  60. 	}
    61. 

  61. ENDENTRY(P)
    62.