Changeset 4584

Timestamp:

Jul 20, 2005, 4:26:39 AM (21 years ago)

Author:

eugene

Message:

added xy second-order moment

File:

• trunk/Ohana/src/opihi/lib.data/starfuncs.c (modified) (5 diffs)

trunk/Ohana/src/opihi/lib.data/starfuncs.c

@@ -4 +4 @@
 
   double *ring;
-  double x, y, x2, y2, I, sky, FWHMx, FWHMy, value, mag;
+  double x, y, x2, y2, xy, I, sky, FWHMx, FWHMy, value, mag, Sxy;
   int i, j, n, Npix2, Nring, Nmax;
   double Npts, gain, dsky2, dmag, peak, offset;
@@ -47 +47 @@
   peak = 0;
   Npts = Nmax = 0;
-  x = y = x2 = y2 = I = 0;
+  x = y = x2 = y2 = xy = I = 0;
   for (i = X - Npix2; i < X + Npix2 + 1; i++) {
     for (j = Y - Npix2; j < Y + Npix2 + 1; j++) {
@@ -56 +56 @@
       x2 += i*i*offset;
       y2 += j*j*offset;
+      xy += i*j*offset;
       I  += offset;
       Npts ++;
@@ -69 +70 @@
   FWHMx = 2.355*sqrt (fabs(x2 / I - x*x));
   FWHMy = 2.355*sqrt (fabs(y2 / I - y*y));
+  Sxy   = xy / I - x*y;
   mag = -2.5*log10(I);
   dmag = sqrt (fabs(1.0 / (gain*I) + Npts*dsky2 / (I*I)));
@@ -78 +80 @@
   set_variable ("SXg", FWHMx);
   set_variable ("SYg", FWHMy);
+  set_variable ("SXYg", Sxy);
   set_variable ("Sg", sky);
   set_variable ("dSg", sqrt (fabs (dsky2)));