1 files changed, 102 insertions, 0 deletions
diff --git a/src/PJ_poly.c b/src/PJ_poly.c
new file mode 100644
index 00000000..04d8cd96
--- /dev/null
+++ b/src/PJ_poly.c
@@ -0,0 +1,102 @@
+#ifndef lint
+static const char SCCSID[]="@(#)PJ_poly.c	4.1	94/02/15	GIE	REL";
+#endif
+#define PROJ_PARMS__ \
+	double ml0; \
+	double *en;
+#define PJ_LIB__
+#include <projects.h>
+PROJ_HEAD(poly, "Polyconic (American)")
+	"\n\tConic, Sph&Ell";
+#define TOL	1e-10
+#define CONV	1e-10
+#define N_ITER	10
+#define I_ITER 20
+#define ITOL 1.e-12
+FORWARD(e_forward); /* ellipsoid */
+	double  ms, sp, cp;
+
+	if (fabs(lp.phi) <= TOL) { xy.x = lp.lam; xy.y = -P->ml0; }
+	else {
+		sp = sin(lp.phi);
+		ms = fabs(cp = cos(lp.phi)) > TOL ? pj_msfn(sp, cp, P->es) / sp : 0.;
+		xy.x = ms * sin(lp.lam *= sp);
+		xy.y = (pj_mlfn(lp.phi, sp, cp, P->en) - P->ml0) + ms * (1. - cos(lp.lam));
+	}
+	return (xy);
+}
+FORWARD(s_forward); /* spheroid */
+	double  cot, E;
+
+	if (fabs(lp.phi) <= TOL) { xy.x = lp.lam; xy.y = P->ml0; }
+	else {
+		cot = 1. / tan(lp.phi);
+		xy.x = sin(E = lp.lam * sin(lp.phi)) * cot;
+		xy.y = lp.phi - P->phi0 + cot * (1. - cos(E));
+	}
+	return (xy);
+}
+INVERSE(e_inverse); /* ellipsoid */
+	xy.y += P->ml0;
+	if (fabs(xy.y) <= TOL) { lp.lam = xy.x; lp.phi = 0.; }
+	else {
+		double r, c, sp, cp, s2ph, ml, mlb, mlp, dPhi;
+		int i;
+
+		r = xy.y * xy.y + xy.x * xy.x;
+		for (lp.phi = xy.y, i = I_ITER; i ; --i) {
+			sp = sin(lp.phi);
+			s2ph = sp * ( cp = cos(lp.phi));
+			if (fabs(cp) < ITOL)
+				I_ERROR;
+			c = sp * (mlp = sqrt(1. - P->es * sp * sp)) / cp;
+			ml = pj_mlfn(lp.phi, sp, cp, P->en);
+			mlb = ml * ml + r;
+			mlp = P->one_es / (mlp * mlp * mlp);
+			lp.phi += ( dPhi =
+				( ml + ml + c * mlb - 2. * xy.y * (c * ml + 1.) ) / (
+				P->es * s2ph * (mlb - 2. * xy.y * ml) / c +
+				2.* (xy.y - ml) * (c * mlp - 1. / s2ph) - mlp - mlp ));
+			if (fabs(dPhi) <= ITOL)
+				break;
+		}
+		if (!i)
+			I_ERROR;
+		c = sin(lp.phi);
+		lp.lam = asin(xy.x * tan(lp.phi) * sqrt(1. - P->es * c * c)) / sin(lp.phi);
+	}
+	return (lp);
+}
+INVERSE(s_inverse); /* spheroid */
+	double B, dphi, tp;
+	int i;
+
+	if (fabs(xy.y = P->phi0 + xy.y) <= TOL) { lp.lam = xy.x; lp.phi = 0.; }
+	else {
+		lp.phi = xy.y;
+		B = xy.x * xy.x + xy.y * xy.y;
+		i = N_ITER;
+		do {
+			tp = tan(lp.phi);
+			lp.phi -= (dphi = (xy.y * (lp.phi * tp + 1.) - lp.phi -
+				.5 * ( lp.phi * lp.phi + B) * tp) /
+				((lp.phi - xy.y) / tp - 1.));
+		} while (fabs(dphi) > CONV && --i);
+		if (! i) I_ERROR;
+		lp.lam = asin(xy.x * tan(lp.phi)) / sin(lp.phi);
+	}
+	return (lp);
+}
+FREEUP; if (P) { if (P->en) pj_dalloc(P->en); pj_dalloc(P); } }
+ENTRY1(poly, en)
+	if (P->es) {
+		if (!(P->en = pj_enfn(P->es))) E_ERROR_0;
+		P->ml0 = pj_mlfn(P->phi0, sin(P->phi0), cos(P->phi0), P->en);
+		P->inv = e_inverse;
+		P->fwd = e_forward;
+	} else {
+		P->ml0 = -P->phi0;
+		P->inv = s_inverse;
+		P->fwd = s_forward;
+	}
+ENDENTRY(P)