From 72452918df38d4a6532beab76a161d5e9c16073c Mon Sep 17 00:00:00 2001
From: Daniel Warner <contact@danrw.com>
Date: Fri, 1 Apr 2011 14:40:44 +0100
Subject: [PATCH] Reverted FindPositionSDP4() to simpler version

---
 SGDP4.cpp | 30 +++++++++++++++++-------------
 main.cpp  |  8 ++++----
 2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/SGDP4.cpp b/SGDP4.cpp
index f7f7691..68c374a 100644
--- a/SGDP4.cpp
+++ b/SGDP4.cpp
@@ -256,12 +256,12 @@ void SGDP4::FindPositionSDP4(Eci& eci, double tsince) {
     /*
      * the final values
      */
-    double e = Eccentricity();
+    double e;
     double a;
     double omega;
     double xl;
     double xnode;
-    double xincl = Inclination();
+    double xincl;
 
     /*
      * update for secular gravity and atmospheric drag
@@ -270,8 +270,6 @@ void SGDP4::FindPositionSDP4(Eci& eci, double tsince) {
     double omgadf = ArgumentPerigee() + i_omgdot_ * tsince;
     const double xnoddf = AscendingNode() + i_xnodot_ * tsince;
 
-    omega = omgadf;
-
     const double tsq = tsince * tsince;
     xnode = xnoddf + i_xnodcf_ * tsq;
     double tempa = 1.0 - i_c1_ * tsince;
@@ -279,17 +277,18 @@ void SGDP4::FindPositionSDP4(Eci& eci, double tsince) {
     double templ = i_t2cof_ * tsq;
 
     double xn = RecoveredMeanMotion();
+    e = Eccentricity();
+    xincl = Inclination();
 
-    /* t, xll, omgasm, xnodes, em, xinc, xn */
-    DeepSpaceSecular(tsince, xmdf, omega, xnode, e, xincl, xn);
+    DeepSpaceSecular(tsince, xmdf, omgadf, xnode, e, xincl, xn);
 
     if (xn <= 0.0) {
         throw new SatelliteException("Error: 2 (xn <= 0.0)");
     }
 
     a = pow(constants_.XKE / xn, constants_.TWOTHRD) * pow(tempa, 2.0);
-
     e -= tempe;
+    
     /*
      * fix tolerance for error recognition
      */
@@ -302,14 +301,18 @@ void SGDP4::FindPositionSDP4(Eci& eci, double tsince) {
     if (e < 1.0e-6)
         e = 1.0e-6;
 
+    /*
     xmdf += RecoveredMeanMotion() * templ;
-    double xlm = xmdf + omega + xnode;
+    double xlm = xmdf + omgadf + xnode;
     xnode = fmod(xnode, Globals::TWOPI());
-    omega = fmod(omega, Globals::TWOPI());
+    omgadf = fmod(omgadf, Globals::TWOPI());
     xlm = fmod(xlm, Globals::TWOPI());
-    double xmam = fmod(xlm - omega - xnode, Globals::TWOPI());
+    double xmam = fmod(xlm - omgadf - xnode, Globals::TWOPI());
+     */
 
-    DeepSpacePeriodics(tsince, e, xincl, omega, xnode, xmam);
+    double xmam = xmdf + RecoveredMeanMotion() * templ;
+
+    DeepSpacePeriodics(tsince, e, xincl, omgadf, xnode, xmam);
 
     /*
      * keeping xincl positive important unless you need to display xincl
@@ -318,10 +321,11 @@ void SGDP4::FindPositionSDP4(Eci& eci, double tsince) {
     if (xincl < 0.0) {
         xincl = -xincl;
         xnode += Globals::PI();
-        omega -= Globals::PI();
+        omgadf -= Globals::PI();
     }
 
-    xl = xmam + omega + xnode;
+    xl = xmam + omgadf + xnode;
+    omega = omgadf;
 
     if (e < 0.0 || e > 1.0) {
         throw new SatelliteException("Error: 3 (e < 0.0 || e > 1.0)");
diff --git a/main.cpp b/main.cpp
index 2a047af..f1d7333 100644
--- a/main.cpp
+++ b/main.cpp
@@ -144,7 +144,7 @@ void RunTle(Tle tle, double start, double end, double inc) {
 
 void RunTest() {
 
-    //#if 0
+#if 0
 
     /*
       #   ------------------ Verification test cases ----------------------
@@ -176,7 +176,7 @@ void RunTest() {
     RunTle(Tle("06251",
             "1 06251U 62025E   06176.82412014  .00008885  00000-0  12808-3 0  3985",
             "2 06251  58.0579  54.0425 0030035 139.1568 221.1854 15.56387291  6774"), 0.0, 2880.0, 120.0);
-
+#endif
 
     /*
     #   MOLNIYA 2-14              # 12h resonant ecc in 0.65 to 0.7 range
@@ -187,7 +187,7 @@ void RunTest() {
             "1 08195U 75081A   06176.33215444  .00000099  00000-0  11873-3 0   813",
             "2 08195  64.1586 279.0717 6877146 264.7651  20.2257  2.00491383225656"), 0.0, 2880.0, 120.0);
 
-
+    return;
     /*
     #   MOLNIYA 1-36              ## fig 12h resonant ecc in 0.7 to 0.715 range
     1 09880U 77021A   06176.56157475  .00000421  00000-0  10000-3 0  9814
@@ -216,7 +216,7 @@ void RunTest() {
     RunTle(Tle("11801",
             "1 11801U          80230.29629788  .01431103  00000-0  14311-1      13",
             "2 11801  46.7916 230.4354 7318036  47.4722  10.4117  2.28537848    13"), 0.0, 1440.0, 360.0);
-    //#endif
+
 
     /*
    #   EUTELSAT 1-F1 (ECS1)## fig lyddane choice in GSFC at 2080 min