/Proj4/PJ_tpeqd.c

http://github.com/route-me/route-me · C · 79 lines · 74 code · 3 blank · 2 comment · 7 complexity · aa81ed3445de429e01f6f85cf7a5f4f7 MD5 · raw file 

    

  1. #ifndef lint
    2. 

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

  3. #endif
    4. 

  4. #define PROJ_PARMS__ \
    5. 

  5. 	double cp1, sp1, cp2, sp2, ccs, cs, sc, r2z0, z02, dlam2; \
    6. 

  6. 	double hz0, thz0, rhshz0, ca, sa, lp, lamc;
    7. 

  7. #define PJ_LIB__
    8. 

  8. #include	"projects.h"
    9. 

  9. PROJ_HEAD(tpeqd, "Two Point Equidistant")
    10. 

  10. 	"\n\tMisc Sph\n\tlat_1= lon_1= lat_2= lon_2=";
    11. 

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

  12. 	double t, z1, z2, dl1, dl2, sp, cp;
    13. 

  13. 

  14. 	sp = sin(lp.phi);
    15. 

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

  16. 	z1 = aacos(P->sp1 * sp + P->cp1 * cp * cos(dl1 = lp.lam + P->dlam2));
    17. 

  17. 	z2 = aacos(P->sp2 * sp + P->cp2 * cp * cos(dl2 = lp.lam - P->dlam2));
    18. 

  18. 	z1 *= z1;
    19. 

  19. 	z2 *= z2;
    20. 

  20. 	xy.x = P->r2z0 * (t = z1 - z2);
    21. 

  21. 	t = P->z02 - t;
    22. 

  22. 	xy.y = P->r2z0 * asqrt(4. * P->z02 * z2 - t * t);
    23. 

  23. 	if ((P->ccs * sp - cp * (P->cs * sin(dl1) - P->sc * sin(dl2))) < 0.)
    24. 

  24. 		xy.y = -xy.y;
    25. 

  25. 	return xy;
    26. 

  26. }
    27. 

  27. INVERSE(s_inverse); /* sphere */
    28. 

  28. 	double cz1, cz2, s, d, cp, sp;
    29. 

  29. 

  30. 	cz1 = cos(hypot(xy.y, xy.x + P->hz0));
    31. 

  31. 	cz2 = cos(hypot(xy.y, xy.x - P->hz0));
    32. 

  32. 	s = cz1 + cz2;
    33. 

  33. 	d = cz1 - cz2;
    34. 

  34. 	lp.lam = - atan2(d, (s * P->thz0));
    35. 

  35. 	lp.phi = aacos(hypot(P->thz0 * s, d) * P->rhshz0);
    36. 

  36. 	if ( xy.y < 0. )
    37. 

  37. 		lp.phi = - lp.phi;
    38. 

  38. 	/* lam--phi now in system relative to P1--P2 base equator */
    39. 

  39. 	sp = sin(lp.phi);
    40. 

  40. 	cp = cos(lp.phi);
    41. 

  41. 	lp.phi = aasin(P->sa * sp + P->ca * cp * (s = cos(lp.lam -= P->lp)));
    42. 

  42. 	lp.lam = atan2(cp * sin(lp.lam), P->sa * cp * s - P->ca * sp) + P->lamc;
    43. 

  43. 	return lp;
    44. 

  44. }
    45. 

  45. FREEUP; if (P) pj_dalloc(P); }
    46. 

  46. ENTRY0(tpeqd)
    47. 

  47. 	double lam_1, lam_2, phi_1, phi_2, A12, pp;
    48. 

  48. 

  49. 	/* get control point locations */
    50. 

  50. 	phi_1 = pj_param(P->params, "rlat_1").f;
    51. 

  51. 	lam_1 = pj_param(P->params, "rlon_1").f;
    52. 

  52. 	phi_2 = pj_param(P->params, "rlat_2").f;
    53. 

  53. 	lam_2 = pj_param(P->params, "rlon_2").f;
    54. 

  54. 	if (phi_1 == phi_2 && lam_1 == lam_2) E_ERROR(-25);
    55. 

  55. 	P->lam0 = adjlon(0.5 * (lam_1 + lam_2));
    56. 

  56. 	P->dlam2 = adjlon(lam_2 - lam_1);
    57. 

  57. 	P->cp1 = cos(phi_1);
    58. 

  58. 	P->cp2 = cos(phi_2);
    59. 

  59. 	P->sp1 = sin(phi_1);
    60. 

  60. 	P->sp2 = sin(phi_2);
    61. 

  61. 	P->cs = P->cp1 * P->sp2;
    62. 

  62. 	P->sc = P->sp1 * P->cp2;
    63. 

  63. 	P->ccs = P->cp1 * P->cp2 * sin(P->dlam2);
    64. 

  64. 	P->z02 = aacos(P->sp1 * P->sp2 + P->cp1 * P->cp2 * cos(P->dlam2));
    65. 

  65. 	P->hz0 = .5 * P->z02;
    66. 

  66. 	A12 = atan2(P->cp2 * sin(P->dlam2),
    67. 

  67. 		P->cp1 * P->sp2 - P->sp1 * P->cp2 * cos(P->dlam2));
    68. 

  68. 	P->ca = cos(pp = aasin(P->cp1 * sin(A12)));
    69. 

  69. 	P->sa = sin(pp);
    70. 

  70. 	P->lp = adjlon(atan2(P->cp1 * cos(A12), P->sp1) - P->hz0);
    71. 

  71. 	P->dlam2 *= .5;
    72. 

  72. 	P->lamc = HALFPI - atan2(sin(A12) * P->sp1, cos(A12)) - P->dlam2;
    73. 

  73. 	P->thz0 = tan(P->hz0);
    74. 

  74. 	P->rhshz0 = .5 / sin(P->hz0);
    75. 

  75. 	P->r2z0 = 0.5 / P->z02;
    76. 

  76. 	P->z02 *= P->z02;
    77. 

  77. 	P->inv = s_inverse; P->fwd = s_forward;
    78. 

  78. 	P->es = 0.;
    79. 

  79. ENDENTRY(P)
    80.