/Proj4/PJ_vandg2.c

http://github.com/route-me/route-me · C · 48 lines · 47 code · 1 blank · 0 comment · 8 complexity · eb0c2b47697ace890fa151116e35b09d MD5 · raw file 

    

  1. #ifndef lint
    2. 

  2. static const char SCCSID[]="@(#)PJ_vandg2.c	4.1	94/02/15	GIE	REL";
    3. 

  3. #endif
    4. 

  4. # define TOL	1e-10
    5. 

  5. # define TWORPI	0.63661977236758134308
    6. 

  6. #define PROJ_PARMS__ \
    7. 

  7. 	int	vdg3;
    8. 

  8. #define PJ_LIB__
    9. 

  9. #include	"projects.h"
    10. 

  10. PROJ_HEAD(vandg2, "van der Grinten II") "\n\tMisc Sph, no inv.";
    11. 

  11. PROJ_HEAD(vandg3, "van der Grinten III") "\n\tMisc Sph, no inv.";
    12. 

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

  13. 	double x1, at, bt, ct;
    14. 

  14. 

  15. 	bt = fabs(TWORPI * lp.phi);
    16. 

  16. 	if ((ct = 1. - bt * bt) < 0.)
    17. 

  17. 		ct = 0.;
    18. 

  18. 	else
    19. 

  19. 		ct = sqrt(ct);
    20. 

  20. 	if (fabs(lp.lam) < TOL) {
    21. 

  21. 		xy.x = 0.;
    22. 

  22. 		xy.y = PI * (lp.phi < 0. ? -bt : bt) / (1. + ct);
    23. 

  23. 	} else {
    24. 

  24. 		at = 0.5 * fabs(PI / lp.lam - lp.lam / PI);
    25. 

  25. 		if (P->vdg3) {
    26. 

  26. 			x1 = bt / (1. + ct);
    27. 

  27. 			xy.x = PI * (sqrt(at * at + 1. - x1 * x1) - at);
    28. 

  28. 			xy.y = PI * x1;
    29. 

  29. 		} else {
    30. 

  30. 			x1 = (ct * sqrt(1. + at * at) - at * ct * ct) /
    31. 

  31. 				(1. + at * at * bt * bt);
    32. 

  32. 			xy.x = PI * x1;
    33. 

  33. 			xy.y = PI * sqrt(1. - x1 * (x1 + 2. * at) + TOL);
    34. 

  34. 		}
    35. 

  35. 		if ( lp.lam < 0.) xy.x = -xy.x;
    36. 

  36. 		if ( lp.phi < 0.) xy.y = -xy.y;
    37. 

  37. 	}
    38. 

  38. 	return (xy);
    39. 

  39. }
    40. 

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

  41. ENTRY0(vandg2)
    42. 

  42. 	P->vdg3 = 0;
    43. 

  43. 	P->inv = 0; P->fwd = s_forward;
    44. 

  44. ENDENTRY(P)
    45. 

  45. ENTRY0(vandg3)
    46. 

  46. 	P->vdg3 = 1;
    47. 

  47. 	P->es = 0.; P->fwd = s_forward;
    48. 

  48. ENDENTRY(P)
    49.