svn-gvsig-desktop / trunk / libraries / libjni-proj4 / src / PJ_robin.c @ 7098
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#ifndef lint
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static const char SCCSID[]="@(#)PJ_robin.c 4.1 94/02/15 GIE REL"; |
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#endif
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#define PJ_LIB__
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#include <projects.h> |
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PROJ_HEAD(robin, "Robinson") "\n\tPCyl., Sph."; |
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#define V(C,z) (C.c0 + z * (C.c1 + z * (C.c2 + z * C.c3)))
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#define DV(C,z) (C.c1 + z * (C.c2 + C.c2 + z * 3. * C.c3)) |
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/* note: following terms based upon 5 deg. intervals in degrees. */
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static struct COEFS { |
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float c0, c1, c2, c3;
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} X[] = {
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1, -5.67239e-12, -7.15511e-05, 3.11028e-06, |
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0.9986, -0.000482241, -2.4897e-05, -1.33094e-06, |
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0.9954, -0.000831031, -4.4861e-05, -9.86588e-07, |
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0.99, -0.00135363, -5.96598e-05, 3.67749e-06, |
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0.9822, -0.00167442, -4.4975e-06, -5.72394e-06, |
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0.973, -0.00214869, -9.03565e-05, 1.88767e-08, |
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0.96, -0.00305084, -9.00732e-05, 1.64869e-06, |
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0.9427, -0.00382792, -6.53428e-05, -2.61493e-06, |
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0.9216, -0.00467747, -0.000104566, 4.8122e-06, |
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0.8962, -0.00536222, -3.23834e-05, -5.43445e-06, |
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0.8679, -0.00609364, -0.0001139, 3.32521e-06, |
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0.835, -0.00698325, -6.40219e-05, 9.34582e-07, |
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0.7986, -0.00755337, -5.00038e-05, 9.35532e-07, |
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0.7597, -0.00798325, -3.59716e-05, -2.27604e-06, |
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0.7186, -0.00851366, -7.0112e-05, -8.63072e-06, |
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0.6732, -0.00986209, -0.000199572, 1.91978e-05, |
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0.6213, -0.010418, 8.83948e-05, 6.24031e-06, |
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0.5722, -0.00906601, 0.000181999, 6.24033e-06, |
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0.5322, 0.,0.,0. }, |
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Y[] = {
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0, 0.0124, 3.72529e-10, 1.15484e-09, |
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0.062, 0.0124001, 1.76951e-08, -5.92321e-09, |
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0.124, 0.0123998, -7.09668e-08, 2.25753e-08, |
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0.186, 0.0124008, 2.66917e-07, -8.44523e-08, |
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0.248, 0.0123971, -9.99682e-07, 3.15569e-07, |
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0.31, 0.0124108, 3.73349e-06, -1.1779e-06, |
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0.372, 0.0123598, -1.3935e-05, 4.39588e-06, |
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0.434, 0.0125501, 5.20034e-05, -1.00051e-05, |
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0.4968, 0.0123198, -9.80735e-05, 9.22397e-06, |
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0.5571, 0.0120308, 4.02857e-05, -5.2901e-06, |
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0.6176, 0.0120369, -3.90662e-05, 7.36117e-07, |
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0.6769, 0.0117015, -2.80246e-05, -8.54283e-07, |
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0.7346, 0.0113572, -4.08389e-05, -5.18524e-07, |
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0.7903, 0.0109099, -4.86169e-05, -1.0718e-06, |
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0.8435, 0.0103433, -6.46934e-05, 5.36384e-09, |
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0.8936, 0.00969679, -6.46129e-05, -8.54894e-06, |
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0.9394, 0.00840949, -0.000192847, -4.21023e-06, |
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0.9761, 0.00616525, -0.000256001, -4.21021e-06, |
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1., 0.,0.,0 }; |
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#define FXC 0.8487 |
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#define FYC 1.3523 |
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#define C1 11.45915590261646417544 |
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#define RC1 0.08726646259971647884 |
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#define NODES 18 |
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#define ONEEPS 1.000001 |
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#define EPS 1e-8 |
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FORWARD(s_forward); /* spheroid */
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int i;
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double dphi;
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i = floor((dphi = fabs(lp.phi)) * C1); |
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if (i >= NODES) i = NODES - 1; |
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dphi = RAD_TO_DEG * (dphi - RC1 * i); |
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xy.x = V(X[i], dphi) * FXC * lp.lam; |
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xy.y = V(Y[i], dphi) * FYC; |
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if (lp.phi < 0.) xy.y = -xy.y; |
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return (xy);
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} |
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INVERSE(s_inverse); /* spheroid */
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int i;
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double t, t1;
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struct COEFS T;
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lp.lam = xy.x / FXC; |
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lp.phi = fabs(xy.y / FYC); |
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if (lp.phi >= 1.) { /* simple pathologic cases */ |
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if (lp.phi > ONEEPS) I_ERROR
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else {
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lp.phi = xy.y < 0. ? -HALFPI : HALFPI;
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lp.lam /= X[NODES].c0; |
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} |
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} else { /* general problem */ |
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/* in Y space, reduce to table interval */
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for (i = floor(lp.phi * NODES);;) {
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if (Y[i].c0 > lp.phi) --i;
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else if (Y[i+1].c0 <= lp.phi) ++i; |
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else break; |
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} |
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T = Y[i]; |
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/* first guess, linear interp */
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t = 5. * (lp.phi - T.c0)/(Y[i+1].c0 - T.c0); |
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/* make into root */
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T.c0 -= lp.phi; |
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for (;;) { /* Newton-Raphson reduction */ |
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t -= t1 = V(T,t) / DV(T,t); |
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if (fabs(t1) < EPS)
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break;
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} |
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lp.phi = (5 * i + t) * DEG_TO_RAD;
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if (xy.y < 0.) lp.phi = -lp.phi; |
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lp.lam /= V(X[i], t); |
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} |
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return (lp);
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} |
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FREEUP; if (P) pj_dalloc(P); }
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ENTRY0(robin) P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)
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