1 files changed, 89 insertions, 0 deletions
diff --git a/src/PJ_eqdc.c b/src/PJ_eqdc.c
new file mode 100644
index 00000000..349266ff
--- /dev/null
+++ b/src/PJ_eqdc.c
@@ -0,0 +1,89 @@
+#ifndef lint
+static const char SCCSID[]="@(#)PJ_eqdc.c	4.2	94/03/16	GIE	REL";
+#endif
+#define PROJ_PARMS__ \
+	double phi1; \
+	double phi2; \
+	double n; \
+	double rho; \
+	double rho0; \
+	double c; \
+	double *en; \
+	int		ellips;
+#define PJ_LIB__
+#include	<projects.h>
+PROJ_HEAD(eqdc, "Equidistant Conic")
+	"\n\tConic, Sph&Ell\n\tlat_1= lat_2=";
+# define EPS10	1.e-10
+FORWARD(e_forward); /* sphere & ellipsoid */
+	P->rho = P->c - (P->ellips ? pj_mlfn(lp.phi, sin(lp.phi),
+		cos(lp.phi), P->en) : lp.phi);
+	xy.x = P->rho * sin( lp.lam *= P->n );
+	xy.y = P->rho0 - P->rho * cos(lp.lam);
+	return (xy);
+}
+INVERSE(e_inverse); /* sphere & ellipsoid */
+	if (P->rho = hypot(xy.x, xy.y = P->rho0 - xy.y)) {
+		if (P->n < 0.) {
+			P->rho = -P->rho;
+			xy.x = -xy.x;
+			xy.y = -xy.y;
+		}
+		lp.phi = P->c - P->rho;
+		if (P->ellips)
+			lp.phi = pj_inv_mlfn(lp.phi, P->es, P->en);
+		lp.lam = atan2(xy.x, xy.y) / P->n;
+	} else {
+		lp.lam = 0.;
+		lp.phi = P->n > 0. ? HALFPI : - HALFPI;
+	}
+	return (lp);
+}
+SPECIAL(fac) {
+	double sinphi, cosphi;
+
+	sinphi = sin(lp.phi);
+	cosphi = cos(lp.phi);
+	fac->code |= IS_ANAL_HK;
+	fac->h = 1.;
+	fac->k = P->n * (P->c - (P->ellips ? pj_mlfn(lp.phi, sinphi,
+		cosphi, P->en) : lp.phi)) / pj_msfn(sinphi, cosphi, P->es);
+}
+FREEUP; if (P) { if (P->en) pj_dalloc(P->en); pj_dalloc(P); } }
+ENTRY1(eqdc, en)
+	double cosphi, sinphi;
+	int secant;
+
+	P->phi1 = pj_param(P->params, "rlat_1").f;
+	P->phi2 = pj_param(P->params, "rlat_2").f;
+	if (fabs(P->phi1 + P->phi2) < EPS10) E_ERROR(-21);
+	if (!(P->en = pj_enfn(P->es)))
+		E_ERROR_0;
+	P->n = sinphi = sin(P->phi1);
+	cosphi = cos(P->phi1);
+	secant = fabs(P->phi1 - P->phi2) >= EPS10;
+	if (P->ellips = P->es > 0.) {
+		double ml1, m1;
+
+		m1 = pj_msfn(sinphi, cosphi, P->es);
+		P->en = pj_enfn(P->es);
+		ml1 = pj_mlfn(P->phi1, sinphi, cosphi, P->en);
+		if (secant) { /* secant cone */
+			sinphi = sin(P->phi2);
+			cosphi = cos(P->phi2);
+			P->n = (m1 - pj_msfn(sinphi, cosphi, P->es)) /
+				(pj_mlfn(P->phi2, sinphi, cosphi, P->en) - ml1);
+		}
+		P->c = ml1 + m1 / P->n;
+		P->rho0 = P->c - pj_mlfn(P->phi0, sin(P->phi0),
+			cos(P->phi0), P->en);
+	} else {
+		if (secant)
+			P->n = (cosphi - cos(P->phi2)) / (P->phi2 - P->phi1);
+		P->c = P->phi1 + cos(P->phi1) / P->n;
+		P->rho0 = P->c - P->phi0;
+	}
+	P->inv = e_inverse;
+	P->fwd = e_forward;
+	P->spc = fac;
+ENDENTRY(P)