Index: branches/eam_branches/ipp-20120627/Ohana/src/addstar/doc/tamas_rings.c
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--- branches/eam_branches/ipp-20120627/Ohana/src/addstar/doc/tamas_rings.c	(revision 34224)
+++ branches/eam_branches/ipp-20120627/Ohana/src/addstar/doc/tamas_rings.c	(revision 34224)
@@ -0,0 +1,59 @@
+
+/* 
+ *  Prototype implementation of the optimal rings 
+ *  by Tamas Budavari <budavari@pha.jhu.edu>
+ *  2012-07-23
+ *
+ *  NOTES:
+ *  - Does only one hemisphere (re-run or mirror)
+ *  - Will leave a hole on top to be covered later
+ *  - Based on PS1 internal draft and the C# code
+ *  - Centers seem to match previous output
+ *  - No further testing has beed done
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+int main(int argc, char* argv[])
+{
+    double d2r = M_PI / 180;
+
+    // parameter 'a' is the cell size in degrees
+    double adeg = 3.955;
+
+    // half of 'a' in radians and its atan
+    double halfa = adeg / 2 * d2r;
+    double halftheta = atan(halfa);
+
+    // loop init
+    double d = 0; // starting Decl. - could change this...
+    int ring = 0; // ring ID
+
+    while (d < M_PI / 2 - halftheta) 
+    {
+        double dm = d - halftheta; // eq.5
+        if (d == 0) dm = 0; // initial
+
+	int m = (int)ceil(M_PI * cos(dm) / halftheta);  // eq.6        
+	double ip = 2 * M_PI / m; // eq.7
+        double dp = atan(tan(d + halftheta) * cos(ip / 2)); // eq.9
+
+	// printf("%d  %d\n", ring, m); // ring & # of cells in that ring
+	int i; // dump centers of the cells
+	for (i=0; i<m; i++)
+	{
+	    // R.A. can use different phase per ring 
+	    double a = i * ip; // + phase (watch wraparound) 
+	    // print Decl. and R.A. in deg
+	    printf(" \t %d   %25.20f   %25.20f\n", i, d/d2r, a/d2r);
+	}
+
+	// advance to next ring
+	d = halftheta + dp;
+	ring++;
+    }
+    return 0;
+}
+