New

git-svn-id: http://svn.osgeo.org/metacrs/proj/trunk@776 4e78687f-474d-0410-85f9-8d5e500ac6b2

1 files changed, 79 insertions, 0 deletions

diff --git a/src/PJ_tpeqd.c b/src/PJ_tpeqd.c
new file mode 100644
index 00000000..ae9eb98a
--- /dev/null
+++ b/src/PJ_tpeqd.c
@@ -0,0 +1,79 @@
+#ifndef lint
+static const char SCCSID[]="@(#)PJ_tpeqd.c	4.1	94/02/15	GIE	REL";
+#endif
+#define PROJ_PARMS__ \
+	double cp1, sp1, cp2, sp2, ccs, cs, sc, r2z0, z02, dlam2; \
+	double hz0, thz0, rhshz0, ca, sa, lp, lamc;
+#define PJ_LIB__
+#include	<projects.h>
+PROJ_HEAD(tpeqd, "Two Point Equidistant")
+	"\n\tMisc Sph\n\tlat_1= lon_1= lat_2= lon_2=";
+FORWARD(s_forward); /* sphere */
+	double t, z1, z2, dl1, dl2, sp, cp;
+
+	sp = sin(lp.phi);
+	cp = cos(lp.phi);
+	z1 = aacos(P->sp1 * sp + P->cp1 * cp * cos(dl1 = lp.lam + P->dlam2));
+	z2 = aacos(P->sp2 * sp + P->cp2 * cp * cos(dl2 = lp.lam - P->dlam2));
+	z1 *= z1;
+	z2 *= z2;
+	xy.x = P->r2z0 * (t = z1 - z2);
+	t = P->z02 - t;
+	xy.y = P->r2z0 * asqrt(4. * P->z02 * z2 - t * t);
+	if ((P->ccs * sp - cp * (P->cs * sin(dl1) - P->sc * sin(dl2))) < 0.)
+		xy.y = -xy.y;
+	return xy;
+}
+INVERSE(s_inverse); /* sphere */
+	double cz1, cz2, s, d, cp, sp;
+
+	cz1 = cos(hypot(xy.y, xy.x + P->hz0));
+	cz2 = cos(hypot(xy.y, xy.x - P->hz0));
+	s = cz1 + cz2;
+	d = cz1 - cz2;
+	lp.lam = - atan2(d, (s * P->thz0));
+	lp.phi = aacos(hypot(P->thz0 * s, d) * P->rhshz0);
+	if ( xy.y < 0. )
+		lp.phi = - lp.phi;
+	/* lam--phi now in system relative to P1--P2 base equator */
+	sp = sin(lp.phi);
+	cp = cos(lp.phi);
+	lp.phi = aasin(P->sa * sp + P->ca * cp * (s = cos(lp.lam -= P->lp)));
+	lp.lam = atan2(cp * sin(lp.lam), P->sa * cp * s - P->ca * sp) + P->lamc;
+	return lp;
+}
+FREEUP; if (P) pj_dalloc(P); }
+ENTRY0(tpeqd)
+	double lam_1, lam_2, phi_1, phi_2, A12, pp;
+
+	/* get control point locations */
+	phi_1 = pj_param(P->params, "rlat_1").f;
+	lam_1 = pj_param(P->params, "rlon_1").f;
+	phi_2 = pj_param(P->params, "rlat_2").f;
+	lam_2 = pj_param(P->params, "rlon_2").f;
+	if (phi_1 == phi_2 && lam_1 == lam_2) E_ERROR(-25);
+	P->lam0 = adjlon(0.5 * (lam_1 + lam_2));
+	P->dlam2 = adjlon(lam_2 - lam_1);
+	P->cp1 = cos(phi_1);
+	P->cp2 = cos(phi_2);
+	P->sp1 = sin(phi_1);
+	P->sp2 = sin(phi_2);
+	P->cs = P->cp1 * P->sp2;
+	P->sc = P->sp1 * P->cp2;
+	P->ccs = P->cp1 * P->cp2 * sin(P->dlam2);
+	P->z02 = aacos(P->sp1 * P->sp2 + P->cp1 * P->cp2 * cos(P->dlam2));
+	P->hz0 = .5 * P->z02;
+	A12 = atan2(P->cp2 * sin(P->dlam2),
+		P->cp1 * P->sp2 - P->sp1 * P->cp2 * cos(P->dlam2));
+	P->ca = cos(pp = aasin(P->cp1 * sin(A12)));
+	P->sa = sin(pp);
+	P->lp = adjlon(atan2(P->cp1 * cos(A12), P->sp1) - P->hz0);
+	P->dlam2 *= .5;
+	P->lamc = HALFPI - atan2(sin(A12) * P->sp1, cos(A12)) - P->dlam2;
+	P->thz0 = tan(P->hz0);
+	P->rhshz0 = .5 / sin(P->hz0);
+	P->r2z0 = 0.5 / P->z02;
+	P->z02 *= P->z02;
+	P->inv = s_inverse; P->fwd = s_forward;
+	P->es = 0.;
+ENDENTRY(P)