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/Proj4/PJ_mbt_fps.c

http://github.com/route-me/route-me
C | 41 lines | 39 code | 2 blank | 0 comment | 3 complexity | c85925fedd16e409b2cb925dbee37078 MD5 | raw file
    

  1. #ifndef lint
    2. 

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

  3. #endif
    4. 

  4. #define PJ_LIB__
    5. 

  5. #include	"projects.h"
    6. 

  6. PROJ_HEAD(mbt_fps, "McBryde-Thomas Flat-Pole Sine (No. 2)") "\n\tCyl., Sph.";
    7. 

  7. #define MAX_ITER	10
    8. 

  8. #define LOOP_TOL	1e-7
    9. 

  9. #define C1 0.45503
    10. 

  10. #define C2 1.36509
    11. 

  11. #define C3 1.41546
    12. 

  12. #define C_x 0.22248
    13. 

  13. #define C_y 1.44492
    14. 

  14. #define C1_2 0.33333333333333333333333333
    15. 

  15. FORWARD(s_forward); /* spheroid */
    16. 

  16. 	double k, V, t;
    17. 

  17. 	int i;
    18. 

  18. 

  19. 	k = C3 * sin(lp.phi);
    20. 

  20. 	for (i = MAX_ITER; i ; --i) {
    21. 

  21. 		t = lp.phi / C2;
    22. 

  22. 		lp.phi -= V = (C1 * sin(t) + sin(lp.phi) - k) /
    23. 

  23. 			(C1_2 * cos(t) + cos(lp.phi));
    24. 

  24. 		if (fabs(V) < LOOP_TOL)
    25. 

  25. 			break;
    26. 

  26. 	}
    27. 

  27. 	t = lp.phi / C2;
    28. 

  28. 	xy.x = C_x * lp.lam * (1. + 3. * cos(lp.phi)/cos(t) );
    29. 

  29. 	xy.y = C_y * sin(t);
    30. 

  30. 	return (xy);
    31. 

  31. }
    32. 

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

  33. 	double t, s;
    34. 

  34. 

  35. 	lp.phi = C2 * (t = aasin(xy.y / C_y));
    36. 

  36. 	lp.lam = xy.x / (C_x * (1. + 3. * cos(lp.phi)/cos(t)));
    37. 

  37. 	lp.phi = aasin((C1 * sin(t) + sin(lp.phi)) / C3);
    38. 

  38. 	return (lp);
    39. 

  39. }
    40. 

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

  41. ENTRY0(mbt_fps) P->es = 0; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)
    42. 

  42.