From cd5bae7871bc0f0bc68b4d2a84703929a7a3c9d1 Mon Sep 17 00:00:00 2001
From: wkj <devnull@localhost>
Date: Wed, 21 Apr 2004 02:16:43 +0000
Subject: Astro with some minor changes to placate Unix.

---
 src/cmd/astro/satel.c | 201 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 201 insertions(+)
 create mode 100644 src/cmd/astro/satel.c

(limited to 'src/cmd/astro/satel.c')

diff --git a/src/cmd/astro/satel.c b/src/cmd/astro/satel.c
new file mode 100644
index 00000000..38206e5f
--- /dev/null
+++ b/src/cmd/astro/satel.c
@@ -0,0 +1,201 @@
+#include "astro.h"
+
+char*	satlst[] =
+{
+	0,
+};
+
+struct
+{
+	double	time;
+	double	tilt;
+	double	pnni;
+	double	psi;
+	double	ppi;
+	double	d1pp;
+	double	peri;
+	double	d1per;
+	double	e0;
+	double	deo;
+	double	rdp;
+	double	st;
+	double	ct;
+	double	rot;
+	double	semi;
+} satl;
+
+void
+satels(void)
+{
+	double ifa[10], t, t1, t2, tinc;
+	char **satp;
+	int flag, f, i, n;
+
+	satp = satlst;
+
+loop:
+	if(*satp == 0)
+		return;
+	f = open(*satp, 0);
+	if(f < 0) {
+		fprint(2, "cannot open %s\n", *satp);
+		satp += 2;
+		goto loop;
+	}
+	satp++;
+	rline(f);
+	tinc = atof(skip(6));
+	rline(f);
+	rline(f);
+	for(i=0; i<9; i++)
+		ifa[i] = atof(skip(i));
+	n = ifa[0];
+	i = ifa[1];
+	t = dmo[i-1] + ifa[2] - 1.;
+	if(n%4 == 0 && i > 2)
+		t += 1.;
+	for(i=1970; i<n; i++) {
+		t += 365.;
+		if(i%4 == 0)
+			t += 1.;
+	}
+	t = (t * 24. + ifa[3]) * 60. + ifa[4];
+	satl.time = t * 60.;
+	satl.tilt = ifa[5] * radian;
+	satl.pnni = ifa[6] * radian;
+	satl.psi = ifa[7];
+	satl.ppi = ifa[8] * radian;
+	rline(f);
+	for(i=0; i<5; i++)
+		ifa[i] = atof(skip(i));
+	satl.d1pp = ifa[0] * radian;
+	satl.peri = ifa[1];
+	satl.d1per = ifa[2];
+	satl.e0 = ifa[3];
+	satl.deo = 0;
+	satl.rdp = ifa[4];
+
+	satl.st = sin(satl.tilt);
+	satl.ct = cos(satl.tilt);
+	satl.rot = pipi / (1440. + satl.psi);
+	satl.semi = satl.rdp * (1. + satl.e0);
+
+	n = PER*288.; /* 5 min steps */
+	t = day;
+	for(i=0; i<n; i++) {
+		if(sunel((t-day)/deld) > 0.)
+			goto out;
+		satel(t);
+		if(el > 0) {
+			t1 = t;
+			flag = 0;
+			do {
+				if(el > 30.)
+					flag++;
+				t -= tinc/(24.*3600.);
+				satel(t);
+			} while(el > 0.);
+			t2 = (t - day)/deld;
+			t = t1;
+			do {
+				t += tinc/(24.*3600.);
+				satel(t);
+				if(el > 30.)
+					flag++;
+			} while(el > 0.);
+			if(flag)
+				if((*satp)[0] == '-')
+					event("%s pass at ", (*satp)+1, "",
+						t2, SIGNIF+PTIME+DARK); else
+					event("%s pass at ", *satp, "",
+						t2, PTIME+DARK);
+		}
+	out:
+		t += 5./(24.*60.);
+	}
+	close(f);
+	satp++;
+	goto loop;
+}
+
+void
+satel(double time)
+{
+	int i;
+	double amean, an, coc, csl, d, de, enom, eo;
+	double pp, q, rdp, slong, ssl, t, tp;
+
+	i = 500;
+	el = -1;
+	time = (time-25567.5) * 86400;
+	t = (time - satl.time)/60;
+	if(t < 0)
+		return; /* too early for satelites */
+	an = floor(t/satl.peri);
+	while(an*satl.peri + an*an*satl.d1per/2. <= t) {
+		an += 1;
+		if(--i == 0)
+			return;
+	}
+	while((tp = an*satl.peri + an*an*satl.d1per/2.) > t) {
+		an -= 1;
+		if(--i == 0)
+			return;
+	}
+	amean = (t-tp)/(satl.peri+(an+.5)*satl.d1per);
+	pp = satl.ppi+(an+amean)*satl.d1pp;
+	amean *= pipi;
+	eo = satl.e0+satl.deo*an;
+	rdp = satl.semi/(1+eo);
+	enom = amean+eo*sin(amean);
+	do {
+		de = (amean-enom+eo*sin(enom))/(1.0-eo*cos(enom));
+		enom += de;
+		if(--i == 0)
+			return;
+	} while(fabs(de) >= 1.0e-6);
+	q = 3963.35*erad/(rdp*(1-eo*cos(enom))/(1-eo));
+	d = pp + 2*atan2(sqrt((1+eo)/(1-eo))*sin(enom/2),cos(enom/2));
+	slong = satl.pnni + t*satl.rot -
+		atan2(satl.ct*sin(d), cos(d));
+	ssl = satl.st*sin(d);
+	csl = pyth(ssl);
+	if(vis(time, atan2(ssl,csl), slong, q)) {
+		coc = ssl*sin(glat) + csl*cos(glat)*cos(wlong-slong);
+		el = atan2(coc-q, pyth(coc));
+		el /= radian;
+	}
+}
+
+int
+vis(double t, double slat, double slong, double q)
+{
+	double t0, t1, t2, d;
+
+	d = t/86400 - .005375 + 3653;
+	t0 = 6.238030674 + .01720196977*d;
+	t2 = t0 + .0167253303*sin(t0);
+	do {
+		t1 = (t0 - t2 + .0167259152*sin(t2)) /
+			(1 - .0167259152*cos(t2));
+		t2 = t2 + t1;
+	} while(fabs(t1) >= 1.e-4);
+	t0 = 2*atan2(1.01686816*sin(t2/2), cos(t2/2));
+	t0 = 4.926234925 + 8.214985538e-7*d + t0;
+	t1 = 0.91744599 * sin(t0);
+	t0 = atan2(t1, cos(t0));
+	if(t0 < -pi/2)
+		t0 = t0 + pipi;
+	d = 4.88097876 + 6.30038809*d - t0;
+	t0 = 0.43366079 * t1;
+	t1 = pyth(t0);
+	t2 = t1*cos(slat)*cos(d-slong) - t0*sin(slat);
+	if(t2 > 0.46949322e-2) {
+		if(0.46949322e-2*t2 + 0.999988979*pyth(t2) < q)
+			return 0;
+	}
+	t2 = t1*cos(glat)*cos(d-wlong) - t0*sin(glat);
+	if(t2 < .1)
+		return 0;
+	return 1;
+}
-- 
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