Index: /trunk/Ohana/src/relastro/src/FitPosStack.c
===================================================================
--- /trunk/Ohana/src/relastro/src/FitPosStack.c	(revision 39376)
+++ /trunk/Ohana/src/relastro/src/FitPosStack.c	(revision 39376)
@@ -0,0 +1,33 @@
+# include "relastro.h"
+
+// find the median of the positions and the error associated with the median
+int FitPosStack (FitAstromResult *fit, FitStats *fitstats) {
+
+  int i;
+
+  // Convert the measurement errors into initial weights.
+  for (i = 0; i < fitstats->Npoints; i++) {
+    fitstats-> Xstack[i] = fitstats->points[i]. X;
+    fitstats->dXstack[i] = fitstats->points[i].dX;
+    fitstats-> Ystack[i] = fitstats->points[i]. Y;
+    fitstats->dYstack[i] = fitstats->points[i].dY;
+  }
+
+  dsortpair (fitstats->Xstack, fitstats->dXstack, fitstats->Npoints);
+  dsortpair (fitstats->Ystack, fitstats->dYstack, fitstats->Npoints);
+  int N = (int)(fitstats->Npoints / 2);
+  if (fitstats->Npoints % 2) {
+    fit->Ro  = fitstats-> Xstack[N];
+    fit->dRo = fitstats->dXstack[N];
+    fit->Do  = fitstats-> Ystack[N];
+    fit->dDo = fitstats->dYstack[N];
+  } else {
+    fit->Ro  = 0.5*(fitstats-> Xstack[N] + fitstats-> Xstack[N+1]);
+    fit->dRo = 0.5*(fitstats->dXstack[N] + fitstats->dXstack[N+1]);
+    fit->Do  = 0.5*(fitstats-> Ystack[N] + fitstats-> Ystack[N+1]);
+    fit->dDo = 0.5*(fitstats->dYstack[N] + fitstats->dYstack[N+1]);
+  }
+
+  return TRUE;
+}
+