Misc. cleanup (strictly non-functional changes)

Changes worth saving from stale old branch (now deleted).

fix_linux_nativelibs_fkjn.sh

@@ -1,14 +1,15 @@
-#!bin/bash
-# Remove *.so.1 files and replace them with links.
+#!/bin/bash
+# Remove *.so.1 files and replace them with links to corresponding *.so files.
 
 cd ~/OVT/ovt/dist_static/natives/Linux/
 
 filename_list=$(ls *.so.1 );
 
 for filename in ${filename_list[@]}
 do
+    # ${string/%substring/replacement}    If $substring matches back end of $string, substitute $replacement for $substring
 	echo "Removing" $filename
 	rm $filename
-	ln -s ${filename%.1} $filename       
+	ln -s ${filename%.1} $filename
 	echo "Creating link "${filename%.1} to $filename
 done

src/ovt/util/Trans.java

@@ -477,8 +477,23 @@ protected static Matrix3x3 geo_gsm_trans_matrix(double mjd, double[] Eccdz) {
 
   public static Matrix3x3 gei_gse_trans_matrix(double mjd) {
     final double[][] gei_gse = new double[3][];
+
+    /* Normal vector to the ecliptic (in GEI).
+     *
+     * ==> Earth's axial tilt: epsilon_OVT = arctan(0.398/0.917)) = 23.4620 degrees 
+     * Compare, Hapgood 1992 (complete reference above), eq (3) & eq between (4) and (5):
+     *     epsilon = 23.439 - 0.013*((MJD-51544.5/36525.0))
+     * J1950 : T_0 = -0.5 ==> epsilon = 23.4455 degrees
+     * J2000 : T_0 =  0   ==> epsilon = 23.4390 degrees
+     * epsilon = epsilon_OVT ==> T_0 = -1.7692 ==> ~J1823 (Earth axial tilt corresponding to year 1823).
+     * NOTE: The inference above does not make use of any movements in the first point of Aries
+     * and only assumes a 1-to-1 correspondence between Earth's axial tilt and time.
+     * Erik P G Johansson 2019-11-07
+     */
     final double eqlipt[] = {   0.0, -0.398, 0.917 };
-    gei_gse[0] = Utils.sunmjd(mjd);                    // NOTE: Time dependent.
+
+    // Can be intrepreted as three (orthonormal) vectors expressed in GEI.
+    gei_gse[0] = Utils.sunmjd(mjd);                    // Time-dependent vector from Earth pointing toward the Sun.
     gei_gse[1] = Vect.crossn(eqlipt, gei_gse[0]);
     gei_gse[2] = Vect.crossn(gei_gse[0], gei_gse[1]);
     final Matrix3x3 m = new Matrix3x3(gei_gse);

src/ovt/util/Utils.java

@@ -160,7 +160,7 @@ public static double[] sunmjd(double mjd) {
 
     /**
      * vector from earth to sun. NOTE: The use of this function in "sunmjd"
-     * implies that the returned value is in GEI.
+     * hints that the returned value is in GEI or GSE.
      */
     public static double[] sun_vect(Julian mjd) {
         return sun_vectJNI(mjd.integer, mjd.fraction);