1 #define PJ_LIB__
2 #include <projects.h>
3
4 PROJ_HEAD(eck1, "Eckert I") "\n\tPCyl., Sph.";
5 #define FC 0.92131773192356127802
6 #define RP 0.31830988618379067154
7
8
s_forward(LP lp,PJ * P)9 static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
10 XY xy = {0.0,0.0};
11 (void) P;
12
13 xy.x = FC * lp.lam * (1. - RP * fabs(lp.phi));
14 xy.y = FC * lp.phi;
15
16 return xy;
17 }
18
19
s_inverse(XY xy,PJ * P)20 static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */
21 LP lp = {0.0,0.0};
22 (void) P;
23
24 lp.phi = xy.y / FC;
25 lp.lam = xy.x / (FC * (1. - RP * fabs(lp.phi)));
26
27 return (lp);
28 }
29
30
freeup_new(PJ * P)31 static void *freeup_new (PJ *P) { /* Destructor */
32 return pj_dealloc(P);
33 }
34
35
freeup(PJ * P)36 static void freeup (PJ *P) {
37 freeup_new (P);
38 return;
39 }
40
41
PROJECTION(eck1)42 PJ *PROJECTION(eck1) {
43 P->es = 0.0;
44 P->inv = s_inverse;
45 P->fwd = s_forward;
46
47 return P
48 ;
49 }
50
51
pj_eck1_selftest(void)52 #ifndef PJ_SELFTEST
53 int pj_eck1_selftest (void) {return 0;}
54 #else
pj_eck1_selftest(void)55
56 int pj_eck1_selftest (void) {
57 double tolerance_lp = 1e-10;
58 double tolerance_xy = 1e-7;
59
60 char s_args[] = {"+proj=eck1 +a=6400000 +lat_1=0.5 +lat_2=2"};
61
62 LP fwd_in[] = {
63 { 2, 1},
64 { 2,-1},
65 {-2, 1},
66 {-2,-1}
67 };
68 XY s_fwd_expect[] = {
69 { 204680.88820295094, 102912.17842606473},
70 { 204680.88820295094, -102912.17842606473},
71 {-204680.88820295094, 102912.17842606473},
72 {-204680.88820295094, -102912.17842606473},
73 };
74
75 XY inv_in[] = {
76 { 200, 100},
77 { 200,-100},
78 {-200, 100},
79 {-200,-100}
80 };
81
82 LP s_inv_expect[] = {
83 { 0.0019434150820034624, 0.00097170229538813102},
84 { 0.0019434150820034624, -0.00097170229538813102},
85 {-0.0019434150820034624, 0.00097170229538813102},
86 {-0.0019434150820034624, -0.00097170229538813102},
87 };
88
89 return pj_generic_selftest (0, s_args, tolerance_xy, tolerance_lp, 4, 4, fwd_in, 0, s_fwd_expect, inv_in, 0, s_inv_expect);
90 }
91
92
93 #endif
94